Do fish need a light cycle?

[wh33t]

Just a quick question. My fish for the most part are in the dark 24 hours a day, should I have a little lamp on a timer for them?

[dufflight]

Aquarium fish tend to do better with a night/day cycle. Not sure if eating fish used in AP do better with the same cycle. Mine get light of a day but the water is deep and shaded if they want to stay in the dark.

[wh33t]

Aquarium fish tend to do better with a night/day cycle. Not sure if eating fish used in AP do better with the same cycle. Mine get light of a day but the water is deep and shaded if they want to stay in the dark.

Interesting! I'll have to try adding a light. Do you know what the deficits are from not having a light cycle? My fish are just goldfish, so they are not for eating.

[dufflight]

I think its more of a problem if they have light 24/7 they get stressed.

[keith_r]

ohio state university did a study and used the light cycle (as well as temp) to induce spawning of yellow perch

[wh33t]

ohio state university did a study and used the light cycle (as well as temp) to induce spawning of yellow perch

Got a link or care to expand a little more?

[urbanfarmer]

Don't give them more than 12 hours of light.

[keith_r]

here's a link to one of the studies... quite a few are available for free.. google is your friend;

http://www.extension.org/mediawiki/files/b/b6/Evaluation_of_off-season_spawning_techniquesn_and_larval_die.pdf

[heetl]

I have a infrared security camera looking right at my fish tank that is on 24/7. I just read tilapia can see in that spectrum. :oops: I guess I'd better turn it off at night.

[urbanfarmer]

I have a infrared security camera looking right at my fish tank that is on 24/7. I just read tilapia can see in that spectrum. :oops: I guess I'd better turn it off at night.
Interesting... but if they can see any heat; wouldn't technically, anything above absolute zero be visible light to them? :lol:

[urbanfarmer]

Interesting! I'll have to try adding a light. Do you know what the deficits are from not having a light cycle? My fish are just goldfish, so they are not for eating.
From what I understand, they just grow slower. Spawning could be another issue depending on the species. Some fish may have problems with no light, but I don't know any offhand.

I have about 2 dozen goldfish that are practically sealed up and have not seen "the light of day" for almost a year (besides feeding time). Maybe fish that are naturally "bottom dwellers" would be less affected? But yea, you just want your fish to poop; so, light may not be an issue for you. I hate to tell you, but it is definitely something else... they're either sick or the water quality is poisoning them. What's your water like? Any signs of problems on the fish? How are they acting? Does your tank smell or taste funny?

[badflash]

I've never seen any evidence or read any publication that indicates fish grow faster with or without light. Light can provide important breeding cues in some species, but that is about it.

[urbanfarmer]

I've never seen any evidence or read any publication that indicates fish grow faster with or without light. Light can provide important breeding cues in some species, but that is about it.
You have it backwards, they grow slower with too much light not faster. They grow the same (normally) in 12/12 versus say 6/18. It may be species dependent.

[keith_r]

here's one study on the growth of yellow perch, best growth with a 16/8 photoperiod (light/dark)

http://www.extension.org/mediawiki/file ... _Guide.pdf (http://www.extension.org/mediawiki/files/4/4a/Yellow_Perch_Culture_Guide.pdf)

[badflash]

Povide evidence. As I said, my experience says no effect. I've never seen anyone do a study on tilapia. Please provide the reference.



I've never seen any evidence or read any publication that indicates fish grow faster with or without light. Light can provide important breeding cues in some species, but that is about it.
You have it backwards, they grow slower with too much light not faster. They grow the same (normally) in 12/12 versus say 6/18. It may be species dependent.

[urbanfarmer]

Povide evidence. As I said, my experience says no effect. I've never seen anyone do a study on tilapia. Please provide the reference.



I've never seen any evidence or read any publication that indicates fish grow faster with or without light. Light can provide important breeding cues in some species, but that is about it.
You have it backwards, they grow slower with too much light not faster. They grow the same (normally) in 12/12 versus say 6/18. It may be species dependent.
Just set up a tank with 24 on 0 off and another tank with 12 on and 12 off with all other variables equal and compare the growth rate after 6-12 months. ;)

[aquaarche]

speaking of fish does anyone know what a good fish is to put in my grow trough that will eat the algae but not the roots of my plants?

[badflash]

Just set up a tank with 24 on 0 off and another tank with 12 on and 12 off with all other variables equal and compare the growth rate after 6-12 months. ;)

I have several tanks with 24/7 light and several with 12/12. I see no difference. Please stop stating things you feel might be true as facts and cite some real evidence.

keith_r's reference says for one species (yellow perch), a longer photo period would be better (too bad they don't say how much).

Cite your evidence please. It doesn't help people to say reasonable things that are not backed up in fact. That is how old wives's tales get spread all over.

[urbanfarmer]

Just set up a tank with 24 on 0 off and another tank with 12 on and 12 off with all other variables equal and compare the growth rate after 6-12 months. ;)

I have several tanks with 24/7 light and several with 12/12. I see no difference. Please stop stating things you feel might be true as facts and cite some real evidence.

keith_r's reference says for one species (yellow perch), a longer photo period would be better (too bad they don't say how much).

Cite your evidence please. It doesn't help people to say reasonable things that are not backed up in fact. That is how old wives's tales get spread all over.
Hm... irony... but you should weigh them (or some kind of measurement) not just try to "see" a difference.

I'm not stating things religiously, I was regurgitating a general conclusion from the large body of empirical evidence collected during scientific research for tilapia (as well as "textbook" information) to answer the poster's question. :mrgreen:

[keith_r]

there have been quite a few studies on the affect of the photoperiod on fish growth..
http://www.medwelljournals.com/fulltext ... 09.760.763 (http://www.medwelljournals.com/fulltext/?doi=javaa.2009.760.763) for trout..
here's an abstract on nile tilapia
http://onlinelibrary.wiley.com/doi/10.1 ... x/abstract (http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2109.2000.00481.x/abstract)

another on nile tilapia
http://www.mendeley.com/research/effect ... ticus-l-2/ (http://www.mendeley.com/research/effects-different-longday-photoperiods-somatic-growth-gonadal-development-nile-tilapia-oreochromis-niloticus-l-2/)

"regurgitating a general conclusion from the large body of empirical evidence" ???
sounds like folklore to me.. hehe

[urbanfarmer]

there have been quite a few studies on the affect of the photoperiod on fish growth..
http://www.medwelljournals.com/fulltext ... 09.760.763 (http://www.medwelljournals.com/fulltext/?doi=javaa.2009.760.763) for trout..
here's an abstract on nile tilapia
http://onlinelibrary.wiley.com/doi/10.1 ... x/abstract (http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2109.2000.00481.x/abstract)

another on nile tilapia
http://www.mendeley.com/research/effect ... ticus-l-2/ (http://www.mendeley.com/research/effects-different-longday-photoperiods-somatic-growth-gonadal-development-nile-tilapia-oreochromis-niloticus-l-2/)

"regurgitating a general conclusion from the large body of empirical evidence" ???
sounds like folklore to me.. hehe
OH, YOU rascal :lol:

Yea, there are literally thousands of studies out there on this particular topic related to fish dating as far back as 40 to 50 years ago.

I'm really busy with exams; so, I can't go digging for the exact sources, but this is a generally accepted assertion in the scientific community (which as with all things science, is subject to change with empirical evidence). I mean, I could go find 1 or 2, but that would be an injustice given the large body of scientific research and empirical evidence to date. I mean, it's even commonly known that fish will grow better under 24/0, but only under short term conditions. Any actual grow out period is 6 to 12 months, and 12/12 is the best way to go.

For the time being, try google. Find specific research studies that discuss growth rate not gonadal development (fecundity is different than getting big fat fish to eat, derp).

Keep looking guys, you'll find it! If not, I will post in a few days. (and I did try searching my archives briefly, but I have THOUSANDS of papers on all things aquaponics, and my search function on my computer is quite limited, one day I'll organize this mess...)

[keith_r]

http://saudibiosoc.com/SJBS/5-2/files/10.pdf

so many sources, so little time

[urbanfarmer]

http://saudibiosoc.com/SJBS/5-2/files/10.pdf

so many sources, so little time
Uh oh you posted something in Arabic... you're going to hear from you know who! :lol:

Good find, that's actually one of the ones I was looking for!

[badflash]

UB-
Quit it. Quit it now. Stop the smoke and mirrors. You are not an expert on the subject, nor am I. I am not pretending to be one. Don't make statements unless you can back them up. Don't deflect by telling people that they can run the experiment themselves. Don't say it is "widely held" or "is generally accepted". That is the tactic used by the global warmers. It isn't true.

If you want to maintain credibility, stick to what you have personally experienced, or cite a trusted source with proper references, not just some stuff parroted on the Internet.

[Bioritize]

@aarchee

http://en.wikipedia.org/wiki/Plecostomus

[Basil1]

@aarchee

http://en.wikipedia.org/wiki/Plecostomus


Actually not the best choice except when young or if one of the more exotic species is used. The common ones get huge, are extremely messy and destructive, terrible algae eaters and can do some serious damage to your other fish. If you can get bushnose plecos fine. Mollies are great at eating algae too if there is not alot of other choices but may be too small for this application.

[larryreinhardt]

Having raised fish for 59 years and owning and operating two fish farms which produced tens of thousands of fish this is my experience - the longer the light is on the more the fish are active burning calories consuming more food and growing bigger. I've never seen the reverse true.

[urbanfarmer]

UB-
Quit it. Quit it now. Stop the smoke and mirrors. You are not an expert on the subject, nor am I. I am not pretending to be one. Don't make statements unless you can back them up. Don't deflect by telling people that they can run the experiment themselves. Don't say it is "widely held" or "is generally accepted". That is the tactic used by the global warmers. It isn't true.

If you want to maintain credibility, stick to what you have personally experienced, or cite a trusted source with proper references, not just some stuff parroted on the Internet.
I was not deflecting. You do that to me all the time; so, I thought it would be funny, but you don't seem amused... :lol: I see, you're one of thoooooose...

ANYWAY, I've got 2 well written books that both state what I have said in my previous posts, not to mention there are hundreds of studies (if not thousands) on the topic. Spend some time looking (keith already found some) and you will see the ample body of empirical evidence in scientific literature.

After I finish up with my studies for the week, I will compile a nice list of more research than you will want to read... :mrgreen:

P.S. I never claimed to be an expert (in fact I said I was regurgitating empirical evidence)... and I don't think the fish will grow faster from global warming, but you might be on to something! :lol: sheesh, you're too much badflash...

[davidstcldfl]

In God we trust; all others bring data.
~ Dr. Edwards Deming
:lol:

[urbanfarmer]

In God we trust; all others bring data.
~ Dr. Edwards Deming
:lol:
Ah, an excellent mantra to live by my friend! :lol:

[urbanfarmer]

I warned you...
PM ME THE ABSTRACT OR RELEVANT CONCLUSION/DATA INFORMATION AND I WILL UPDATE THIS


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Barlow, C.G., Pearce, M.G., Rodgers, L.J., Clayton, P., 1995. Effects of photoperiod on growth, survival and
feeding periodicity of larval and juvenile barramundi Lates Calcarifer (Bloch). Aquaculture 138, 159– 168.

Biswas, A.K., Takeuchi, T., 2002. Effect of different photoperiod cycles on metabolic rate and energy loss of both
fed and unfed adult tilapia Oreochromis niloticus: Part II. Fish. Sci. 68, 543– 553.

To study the influence of different photoperiod cycles on the metabolic rate and energy loss of fed and unfed adult tilapia Oreochromis niloticus (bodyweight 102–107 g) at 28°C, four photoperiod cycles (i.e. 3L : 3D, 6L : 6D, 12L : 12D, and 24L : 24D) were applied. A computer-operated respirometer with a closed tank was used so as to prevent water from condensing from the air or evaporating into the air. A photoperiod-mediated metabolic cycle was demonstrated during the routine state in which the metabolic rate was higher during the light phase compared with during the dark phase for all photoperiods. The combined effects of photoperiod and feeding episodes acted as a strong Zeitgeber (cue or synchronizer) for synchronizing the daily rhythm in fed fish. Fish exposed to short photoperiod cycles showed a higher metabolic rate and energy loss compared with those exposed to longer photoperiod cycles. Mean oxygen consumption in the fed and unfed fish were 295.7 mg/kg per h and 149.8 mg/kg per h, respectively, during the 3L : 3D period; 286.5 mg/kg per h and 143.3 mg/kg per h during the 6L : 6D period; 262.2 mg/kg per h and 130.3 mg/kg per h during the 12L : 12D period; and 238.3 mg/kg per h and 120.4 mg/kg per h during the 24L : 24D period. The highest post-prandial increase in energy loss was recorded during the 3L : 3D period (56.2 kJ/kg per day), followed by 55.1 kJ/kg per day during the 6L : 6D period, 50.7 kJ/kg per day during the 12L : 12D period, and 45.4 kJ/kg per day during the 24L : 24D period. The study’s results demonstrated that the fish conserve energy when raised under longer photoperiod cycles.


Biswas, A.K., Endo, M., Takeuchi, T., 2002. Effect of different photoperiod cycles on metabolic rate and energy
loss of both fed and unfed young tilapia Oreochromis niloticus: Part I. Fish. Sci. 68, 465– 477.

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[The effect of] daylength appears much more important. Many species, including both marine species and salmonids, react to photoperiod treatments and long daylength stimulates growth. The most studied species is the Atlantic salmon, which is very sensitive, both during the freshwater stage, with the parr-smolt transformation very dependent on the photoperiod, and also in sea water. In this last condition, lighting also influences early maturation. An important point is to be certain that light affects fish growth through a better food conversion efficiency and not just through stimulated food intake. Also included in this review is a discussion about the endolymph-otolith system, which is very sensitive to daylight and seasonal cycles and a review of the present knowledge on the involvement of light influence on hormone levels (melatonin, somatotropin, thyroid hormones and other hormones).


Biology and Culture of Tilapias. Proc. 7th ICLARM Conf., Manila, Philippines. International Center for
Living Aquatic Resources Management, Manila, Philippines, pp. 119– 128.

De Silva, S.S., Gunasekera, R.M., Keembiyahetty, R.M., 1986. Optimum ration and feeding frequency in
Oreochromis niloticus young. In: Mclean, J.L., Dizon, L.B., Hosillos, L.V. (Eds.), The First Asian Fisheries
Forum. Asian Fisheries Society, Manila, Philippines, pp. 559– 564.

Duray, M., Kohno, H., 1988. Effects of continuous lighting on growth and survival of first-feeding larval
rabbitfish Siganus guttatus. Aquaculture 109, 311 –321.

Duston, J., Saunders, R.L., 1990. The entrainment role of photoperiod on hypoosmoregulatory and growthrelated
aspects of smolting in Atlantic salmon (Salmo salar). Can. J. Zool. 68, 707– 715.

El-Sayed, A.-F.M., 2002. Effects of stocking density and feeding levels on growth and feed efficiency of Nile
tilapia (Oreochromis niloticus L.) fry. Aquac. Res. 33, 621– 626.
400 A.-F.M. El-Sayed, M. Kawanna / Aquaculture 231 (2004) 393–402

Fielder, D.S., Bardsley, W.J., Allan, G.L., Pankhurst, P.M., 2002. Effect of photoperiod on growth and survival of
snapper Pagrus auratus larvae. Aquaculture 211, 135– 150.

Folkvord, A., Ottera°, H., 1993. Effects of initial size distribution, day length and feeding frequency on growth,
survival and cannibalism in juvenile Atlantic cod (Gadus morhua L.). Aquaculture 114, 243–260.
Food and Agriculture Organization of the United Nations (FAO), 2002. FAO FishStat plus. Aquaculture Production
1970– 2000. Rome, Italy.

Fuchs, J., 1978. Influence de la photoperiode sur la croissance et la survie de la larve et du juvenile de sole (Solea
solea) en elevage. Aquaculture 15, 63– 74.

Gill, J.L., 1981. Design and Analysis of Experiments in Animal and Medical Sciences, vol. VI. The Iowa State
Univ. Press, Ames, IA, U.S.A, p. 409.

Gross, W.L., Roelofs, E.W., Fromm, P.O., 1995. Influence of photoperiod on growth of green sunfish, Lepomis
cyanellus. J. Fish. Res. Board Can. 22, 1379– 1386.

Hallara°ker, H., Folkvord, A., Stefansson, S.O., 1995. Growth of juvenile halibut (Hippoglossus hippoglossus)
related to temperature, day length and feeding regime. Neth. J. Sea Res. 34, 139– 147.

Harbott, B.J., 1975. Preliminary observations on the feeding of Tilapia nilotica Linn. Lake Rudolf. Afr. J.
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Imsland, A., Folkvord, A.F., Steffansson, S.O., 1995. Growth, oxygen consumption and activity of juvenile
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149–159.

Imsland, A.K., Folkvord, A.F., Jo´nsdo´ ttir, O.D.B., Steffansson, S.O., 1997. Effects of exposure of extended
photoperiods during the first winter on long-term growth and age at first maturity in turbot (Scophthalmus
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Kiyono, M., Hirano, R., 1981. Effects of light on the feeding and growth of black porgy, Mylio macrocephalus
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M.R. (Eds.), Proc. Aquaculture Brazil ’98. Sustainable Development, vol. 2, pp. 561–569.

Muir, J., Van Rijn, J., Hargreaves, J., 2000. Production in intensive and recycle systems. In: Beveridge,
M.C.M., McAndrew, B.J. (Eds.), Tilapias: Biology and Exploitation. Kluwer Academic Publishing, Great
Britain, pp. 405– 445.

Philippart, J.C., Ruwet, J.C., 1982. Ecology and distribution of tilapias. In: Pullin, R.S.V., Lowe McConnell, R.H.
(Eds.), The Biology and Culture of Tilapias. Proc. 7th ICLARM Conf., Manila, Philippines. International
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Porter, M.J.R., Duncan, N., Handeland, S.O., Stefansson, O., Bromage, N.R., 2001. Temperature, light intensity
and plasma melatonin levels in juvenile Atlantic salmon. J. Fish Biol. 58, 431– 438.
Purchase, C.F., Boyce, D.L., Brown, J.A., 2000. Growth and survival of juvenile flounder Pleuronectes ferrugineus
(Storer) under different photoperiods. Aquac. Res. 31, 547– 552.

Ridha, M.T., Cruz, E.M., 2000. Effect of light intensity and photoperiod on Nile tilapia Oreochromis niloticus.
Aquac. Res. 31, 609– 617.

Ross, L.G., McKinney, R.W., 1988. Photoperiod mediated variation in respiratory rate of Oreochromis niloticus
and its implication for tilapia culture. In: Pullin, R.S.V., Bhukaswan, T., Tonguthai, K., Maclean, J.L. (Eds.),
The 2nd Int. Symp. on Tilapia in Aquaculture. Bangkok, Thailand. ICLARM Conf. Proc., vol. 15. International
Center for Living Aquatic Resources Management, Manila, Philippines, pp. 421– 428.

Saunders, R.L., Henderson, E.B., Harmon, P.R., 1985. Effects of photoperiod on juvenile growth and smolting of
Atlantic salmon and subsequent survival and growth in sea cages. Aquaculture 45, 55– 66.

Silva-Garcia, A.J., 1996. Growth of juvenile gilthead seabraem (Sparus auratus L.) reared under different
photoperiod regimes. Isr. J. Aquac.-Bamidgeh 48, 84– 93.

Siraj, S.S., Kamaruddin, Z., Satar, M.K.A., Kamarudin, M.S., 1988. Effects of feeding frequency on growth food
conversion and survival of red tilapia (Oreochromis mossambicus/O. niloticus) hybrid fry. In: Pullin, R.S.V.,
A.-F.M. El-Sayed, M. Kawanna / Aquaculture 231 (2004) 393–402 401

Bhukaswan T., Tonguthai, K., Maclean, J.L. (Eds.), The 2nd Int. Symp. On Tilapia in Aquaculture. Bangkok,
Thailand. ICLARM Conf. Proc., vol. 15. International Center for Living Aquatic Resources Management,
Manila, Philippines, pp. 383– 386.

Tandler, A., Helps, S., 1985. The effects of photoperiod and water exchange rate on growth and survival of
gilthead seabream (Sparus auratus, Linnaeus; Sparidae) from hatching to metamorphosis in mass rearing
systems. Aquaculture 48, 81– 82.

[urbanfarmer]

I have read the following books, and I have noted the relevant pages:

Tilapia: biology, culture, and nutrition (pg 376-377)
Chhorn Lim, Carl D. Webster

Tilapia culture (pg 123-124)
Abdel-Fattah M. El-Sayed

The above books were compiled with, and represent hundreds and hundreds of research studies. I consider the information in those books "expert" knowledge, and I will go a step further and consider the authors authorities on the topic. My original statement regarding the 12/12 for optimum growth is stated in the above books (even though I read it in a few studies prior to purchasing these books).

[urbanfarmer]

Some more:

Watanabe, W.O., Woolridge, C.A., Daniels, H.V. 2006. Progress toward year-round spawning of southern flounder broodstock by manipulation of photoperiod and temperature. Journal of the World Aquaculture Society. Vol. 37, issue 3: 256-272

Rocha, M.J., Arukwe, A., Kapoor, B.G. 2008. Fish Reproduction. (book).

Bonnet, E., et al. 2007. Characterization of rainbow trout egg quality: A case study
using four different breeding protocols, with emphasis on the incidence of embryonic malformations. Theriogenology 67: 786-794

Norberg, B. et al. 2004. Photoperiod regulates the timing of sexual maturation, spawning, sex steroid and thyroid hormone profiles in the Atlantic cod (Gadus morhua). Aquaculture 229: 451-467

El-Sayed, A-F.M. et Kawanna, M. 2007. Effects of photoperiod on growth and spawning
efficiency of Nile tilapia (Oreochromis niloticus L.) broodstock in a recycling system. Aquaculture Research 38 :1242-1247

Carillo, M. 2007. Environmental control of fish reproduction with special reference to control of puberty and precocity. Presentation.

[urbanfarmer]

And more...

Allen, J.RM. and Wootton, RJ. 1982. The
effect of ration and temperature on the
growth of the three-spined stickleback
Gasterosteus aculeatus (L.). J Fish
Bioi. 20: 409-422.

Brauer, E.P. 1982. The photoperiod control
of coho salmon smoltification.
Aquaculture 28: 105-111.

Degani, G.; Ben-Zvi, Y. and Levanon, D.
1989. The effect of different protein
levels and temperatures on feed
utilization, growth and body
composition of Claris gariepinus
(Burchell, 1822). Aquaculture 76:
293-301.

Komourdjian, M.P.; Saunders, RL. and
Fenwick, J.C. 1976. Evidence for the
role of growth hormones as a part of a
light-pituitary axis' in growth and
smoltification of Atlantic salmon
Salmo salar. Can. J Zool. 54: 544-
551.

Kristinsson, J.B.; Saunders, RL. and Wiggs,
A.J. 1985. Growth dynamics during
the development of bimodal lengthfreqency
distribution in juvenile
Atlantic salmon Salmo salar (L.).
Aquaculture 45: 1-20.

Lundqvist, H. 1980. Influence of
photoperiod on growth in Baltic
salmon parr Salmo solar (L.) with
special reference to the effect of
precocious sexual maturation. Can. J.
Zool. 58: 940-944.

Rottiers, n.v. 1992. Effects of day length
and cleaning regimen on the growth of
yearling parr Atlantic salmon. The
progressive fish culturist 54: 69-72.
Saunders, RL.; and Henderson, E.B. 1970.
Influence of photoperiod on smolt
development and growth of Atlantic
salmon Salmo solar. J. Fish. Res.
Board Can. 27: 1295-1311.

Saunders, RL.; Henderson, E.B. and
Harmon, P. R 1985. Effects of
photoperiod on juvenile growth and
smolting of Atlantic salmon and
subsequent survivaland growth in sea
cages. Aquaculture 45: 55-66.

Saunders, R.L. and Henderson, E.B. 1988.
Effect of constant day length on
sexual maturation and growth of
Atlantic salmon Salmo solar parr.
Can. J. Fish. Aquat. Sci. 45: 60-64.

Schreck, C.B. 1982. Stress and rearing of
salmonids.Aquaculture 28: 241-9.

Trzebiatowski, R; Filipiak, 1. and
Jakubowski, R 1981. Effect of stock
density on growth and survival of
rainbow trout Salmo gairdneri
(Rich.). Aquaculture 22: 289-295.
Villarreal, c.A.; Thorpe, 1.E. and Miles,
M.S. 1988. Influence of photoperiod
on growth changes in juvenile Atlantic
salmon, Salmo solar (L.) Journal of
Fish Biology 33: 15-30.

[urbanfarmer]

I may have to write a tutorial on how to find research... I may not always be around. You guys have to be self-sufficient to keep things going around here! :mrgreen:

I'm running out of "stuff" to contribute around here anyway. :lol:

[urbanfarmer]

http://saudibiosoc.com/SJBS/5-2/files/10.pdf

so many sources, so little time
And let's not forget this one, which keith found before anyone else posted it!


but the mean growth rates under LD 6:6 and LD 12:12 were higher than under LD 24:0


Body weight, GR and SGR became the highest under LD 12: 12 after the first two months until the end of the experiment.

[aquaarche]

@aarchee

http://en.wikipedia.org/wiki/Plecostomus

they are known as Janitor fish here.

These guys eat lettuce and kale. are we sure they wont eat the roots of the plants in the grow beds? I thing they may be a bit much seeing they may suck apart the bottom of my Styrofoam float.

A large Mollie that might work.

Any other ideas?

currently I have one of my Tilapia in there but they are known to eat the roots when the roots begin to expand pass the net gravel pot.

[Basil1]

@aarchee

http://en.wikipedia.org/wiki/Plecostomus

they are known as Janitor fish here.

These guys eat lettuce and kale. are we sure they wont eat the roots of the plants in the grow beds? I thing they may be a bit much seeing they may suck apart the bottom of my Styrofoam float.

A large Mollie that might work.

Any other ideas?

currently I have one of my Tilapia in there but they are known to eat the roots when the roots begin to expand pass the net gravel pot.


As algae does not have a lot of nutritional value and would take a considerable amount to sustain a large pleco it probably will go after the roots. Also known for sucking off the slime coat of fish leaving them more susceptible to diseases.

[davidstcldfl]

In God we trust; all others bring data.
~ Dr. Edwards Deming
:lol:
Ah, an excellent mantra to live by my friend! :lol:
I thought you'd like it... :D

About your new avatar...looks about right, but the hair needs to be more curly... :P .. :lol:



AT Basil1 .... :lol: ...I like your new avatar too... :D

[keith_r]

from what i've found over the last few days, is that the photoperiod is an important factor in growth, and there have been studies done with several species w/ different lighting times..
i've concluded that i'll investigate whatever species i'm growing, and figure out what works best for me..
i've been contemplating working with my yp and trying to induce a spawn this winter.. just picked up a free 55 gal tank, so i'm up to 5 tanks, and the pool.. but i gotta get my gb's on line before i do much more

[urbanfarmer]

About your new avatar...looks about right, but the hair needs to be more curly... :P .. :lol:
:lol: Maybe it will straighten out some when I get old!!!


from what i've found over the last few days, is that the photoperiod is an important factor in growth, and there have been studies done with several species w/ different lighting times..
i've concluded that i'll investigate whatever species i'm growing, and figure out what works best for me..
i've been contemplating working with my yp and trying to induce a spawn this winter.. just picked up a free 55 gal tank, so i'm up to 5 tanks, and the pool.. but i gotta get my gb's on line before i do much more
Yea, it does depend on so many factors. Light intensity, spectrum of light (there are studies on just the colors, weird but interesting), and probably things not studied like UV. Fish species, stage of life cycle, even genetic factors.

Those new plasma lights mimic the spectrum of the sun pretty well, but nothing will match the sun's intensity.

Most spawning studies appear to be done with low intensity lighting. I think this all comes from the earlier studies in the 1950's when they associated spawning behaviors with the extra light from the moon during seasons.

[badflash]

Bristle nosed plecos are the best for clean-up. They clean up well, and only get to about 4".

My conclusion about photoperiod is that on its own is does very little for the fish. It can make an abundance of food in the wild which can then contribute to growth. In an aquaponic setting, it isn't worth much for the fish, but could help your plants.

UF, I find your deflecting comment quite curious. Please site some examples, or is this another of your deflections?

[urbanfarmer]

I posted the references at your request, did you check?


My conclusion about photoperiod is that on its own is does very little for the fish. It can make an abundance of food in the wild which can then contribute to growth. In an aquaponic setting, it isn't worth much for the fish, but could help your plants.
Okay... but, 24 hours of light is clearly not good for some animals and the research cited states 24/0 cycle slows growth in tilapia under long term grow out conditions. Is there a reason you are still stating contradicting statements without proof in lieu of the ample empirical evidence????

[badflash]

I appreciate the overload of data. I was asking for examples of me deflecting, not more data.

I never stated that 24/0 was beneficial. I stated I don't think it matters all that much, and isn't worth the effort. In the cases I read with tiliapia involved the photoperiod it did not significantly effect growth rate when isolated from other factors. It will take me some time to read through your list.

As I have said, I see little or no difference between my fish that are 24/0 and ones that are 12/12 or 0/24. Did you find one of the ones you cited that show it does make a statistically and economic significant difference?

[urbanfarmer]

I appreciate the overload of data. I was asking for examples of me deflecting, not more data.

I never stated that 24/0 was beneficial. I stated I don't think it matters all that much, and isn't worth the effort. In the cases I read with tiliapia involved the photoperiod it did not significantly effect growth rate when isolated from other factors. It will take me some time to read through your list.

As I have said, I see little or no difference between my fish that are 24/0 and ones that are 12/12 or 0/24. Did you find one of the ones you cited that show it does make a statistically and economic significant difference?
[...]

[urbanfarmer]

With regards to your other point, if there's no benefit between 12/12 and 24/0, great! If there is, I would like to know about it and maybe WHY if there is research into it. You make a good point about significance. It may not be a significant difference, which makes it nearly trivial. However, when modern research states it is significant it is with a high degree of certainty (P = 0.05). From there we have to examine the cost for a commercial operation or the convenience for a hobbyist situation (sometimes the cost too). I'm sure if David could grow fish twice as fast by screwing in a 10 Watt CFL bulb and keeping it on at night, he would go for it.

Of course my first point in all of this is that you get optimal growth at 12/12 and that 24/0 hurts growth. Light doesn't make tilapia grow fast, but too much light slows their growth. Your FCR (feed conversion ratio) starts to drop as well meaning you have to feed them more to sustain growth.

So you see, through these exchanges of ideas supported by empirical data we can all learn, and I have learned a lot from most of my exchanges on here. But, you need to learn not to discredit someone else so quickly if you are not willing to support your claims. If you have a formal education in aquaculture, fine, but to my knowledge you do not. I myself have only taken a few courses in aquaculture, but many more in botany, soils, chemistry, biology, etc. The only times I state something as fact without reference is because I learned it out of a TEXTBOOK (not a regular book). The difference is, textbooks reflect our generally accepted principles in science, which means there's hundreds if not thousands of research studies published on it, and usually it represents decades if not centuries of scientific progress.