Are you considering raising Hybrid Tilapia?

[jackalope]

Are you considering raising Hybrid Tilapia? This is why I won't consider it!

This comment is aimed specifically at the Tilapia that are either de-sexed using drugs or chemicals, or those using the so-called “Supermale.” This is not aimed at hybrids of pure strain O.Aurea, O.Nilotica, O.Mossambicus, or O. Hornorum. If you are raising them commercially to sell, that's your lookout, but if you're raising them to feed to your own family, I'd do some research on them if I were you! If you buy hybrids, make sure they come from pure strain stock!

First off, I wouldn't want to put something in my mouth, nevertheless my stomach that might have been a female, but was chemically altered to make it a male. That kind of hybridizing just leads to problems, diseases, malformations, or chemical imbalances 20 or 30 years down the road. That's why we've got illnesses like Alzheimers (aluminum cooking utensils), GMO foods (cancers, allergies), Brucellosis (Mad Cow disease) now proven to cause brain disease in humans ...... etc., etc., etc.. I have found some research on the chemicals used (Synthetic Steroids, Androgens, such as MT, hormones, Human and Simian (ape and monkey) viruses, mixed with alcohol, fish oil, or Vegetable oil, but how long do they stay in the fish's body, and can they eventually build up in the body of the humans that eat them? I haven't been able to find any research that answers that question ! Over 95% of all*Tilapia today are raised for commercial food production, and*are usually*either genetically or chemically altered to produce the faster growing males,*PLUS they*are normally fed diets that often contain hormones and dangerous chemicals.

And how do they reverse the sex chemically? Here's a couple of quotes:

“The most commonly used synthetic estrogens for sex reversal are the non-steroidal estrogens, ethynylestradiol (EE) and diethylstibestrol (DES). DES is the more potent and once was used as a growth promotant in livestock until banned by the US Food and Drug Administration in 1979. Both are carcinogens. ”

Let's see, the FDA bans it for livestock, then allows it for the fish we're going to eat ..... how does that work?

Then, of course, there's the “fry bath” where the fry are dipped once or twice in testosterone, mestanalone, or estrogen for a period so that they can reverse the sex of the fry.....

“Bath treatments with estrogens have not successfully defeminized tilapia. Rosenstein and Hulata (1993) treated O. mossambicus with 17alpha-methyltestosterone over a range of concentrations and durations with no effect on the sex ratios. Toxicity is an issue in estrogen treatments. Eckstein and Spira (1965) reported high mortality of O. aureus fry when given stilbestrol diphosphate baths at 400–1000 :g/l. ”

Of course, the food suppliers want to help out the growers, so they provide the treated feeds and good advice ......

“Since male Tilapia grow faster than females, it is advisable to use an all male population. Many Tilapia growers purchase all male sex-reversed Tilapia from fingerling producers who specialize in sex-reversal. - Purina Mills”


The “Supermale” Hybrid.
I found some research on this that was very interesting. The problem with the super male is that the offspring, which do grow rapidly, are a very inferior fish and successive generations* produce*poorer and poorer quality fish and breeding colonies must be constantly replaced. One thing you will rarely be told about offspring from these "Super Males" is that to*achieve the rapid growth, the large-scale food producers must feed diets supplemented with hormones such as testosterone and/or cancer causing chemicals that we end up eating!

A Cuban research paper has shown what is used to produce these “Supermales” ......
“ tiGH - The Tilapia Growth hormone gene cassette for Tilapia, Oreochromis hornorum hybrids is made up of : P: Human Cytomegalovirus G: Tilapia growth hormone cDNA and T: Simian virus 40 poly A site

tiGH - (1)The Tilapia Growth Hormone gene cassette for Tilapia, Oreochromis niloticus hybrids is made up of: P: Ocean pout antifreeze protein G: Chinook salmon growth hormone cDNA T: Ocean pout antifreeze protein 3' region

tiGH - (2)The Tilapia Growth Hormone gene cassette for Tilapia, Oreochromis niloticus hybrids is made up of: P: Tilapia L18 ribosomal protein promoter G: Tilapia growth hormone gene T: Tilapia poly (A) and termination signal

From the book, Genetically engineered food by Knut Heller:”

"Growth is a complex process in fish. This study was designed to test the effect of different levels of recombinant tilapia growth hormone (tiGH) injected intraperitoneally in juvenile hybrid tilapia Oreochromis hornorum. Tilapia GH cDNA was cloned from hybrid O. hornorum tilapia. The mature protein was expressed in E. coli under regulation of the phage T7 promoter. The E. coli-derived tiGH was partially purified to 67% purity and, following renaturation, was shown to be biologically active in in vivo and in vitro assays. Recombinant tiGH stimulated extracellular matrix synthesis as shown by 35S-sulfate uptake in ceratobranchial cartilage explants. Zero, 0.1, 0.5 and 2.5 &#55g tiGH/g body weight (gbw) were injected in tilapia, and the effects on the growth-promoting action, hepatosomatic index (HSI), and mRNA insulin-like growth factor (IGF) induction were measured. A significant increase in the body weight (P < 0.05) and length (P < 0.01) was observed in tilapia receiving 0.5 &#55g tiGH/gbw. However, tilapia receiving 0.1 and 2.5 &#55g tiGH/gbw did not show an increase in body weight and length with respect to the control group receiving BSA injections. Binding sites for the recombinant tiGH were identified in the liver. Consistent with its somatotropic actions, the IGF mRNA induction was observed in the groups injected with 0.1 and 0.5 &#55g tiGH/gbw (P < 0.05). No significant increase in the HSI was detected in the injected groups when compared to the control group. These results demonstrated that the injection of biologically active E. coli-derived tiGH produces physiological changes in juvenile tilapia that ultimately resulted in a growth-promoting action only at a dose of 0.5 &#55g tiGH/gbw. - Journal of Marine Biotechnology, Vol. 6, No. 3. (1 August 1998), pp. 142-151."

Now I don't know about you, but I'm really not into the idea of having Human virus' and monkey virus' put into my food - talk about monkey pus and turkey turds, this stuff doesn't sound good at all . Then to clean this witches brew, they purify it in E.Coli – I'm confused, I thought E.Coli wasn't a good thing!

[badflash]

The truly silly thing is that there is no need to grow monosex fish. If you grow them in simple mesh covered cages made of PVC pipe the keeps the fish from finding a flat bottom, they can't spawn. This allows the females to put their energy into growth rather than raising fry. Females grown in cage culture will get as large as the males and you'll have no recruits.

Cross species hybridization is a lot of trouble as you need to keep two separate strains of pure fish, but the rate of growth makes up for it if you are doing this on a large scale.

[jackalope]

The truly silly thing is that there is no need to grow monosex fish. If you grow them in simple mesh covered cages made of PVC pipe the keeps the fish from finding a flat bottom, they can't spawn. This allows the females to put their energy into growth rather than raising fry. Females grown in cage culture will get as large as the males and you'll have no recruits.

You've mentioned that before, and I was thinking of that as I did the research ..... it seems to me that it would be so much more inexpensive and more efficient to just line the bottom 2" or so of the tank with PVC or stainless steel screen, underneath that screen could be crays or other bottom feeders that would feed on the eggs and left-over food that drops to the bottom.

Cross species hybridization is a lot of trouble as you need to keep two separate strains of pure fish, but the rate of growth makes up for it if you are doing this on a large scale.

I wouldn't think it would be a huge problem for large commercial operations to keep breeding pairs of pure strains, rather than having to buy fry/fingerlings for each growing cycle. To me, that would just be one of those necessary expenses

[rfeiller]

it isn't a big deal to keep seperate bloodlines or strains going. i maintained several seperate bloodlines of discus and would cross the F1 progeny to maintain the fertility and bolster the immune system when i was raising them commercially.

once females start spawning, and they will produce eggs with or without a male present, their growth slows drastically in cichlids. females can be brought into spawning cycle by water temp, water quality, altering pH, food conditioning, and other females in cycle in the same water system. fish will spawn if all conditions are right and if the conditions are extremely poor to preserve the species.

a closed system like you all use allows the hormones and feramones to build up in the water; they are not removed by plants, gravel or even for that matter with GAC (granular activated carbon).

i played with mossambicas for the aquarium industry in '72-75. no market, but they were extremely intelligent fish that were easy to train to thump a device to get food and to run mazes.

[badflash]

It is a bigger deal than you think. Tilapia are a much bigger fish and have larger needs. You have to keep separate water systems as somehow babies make it through any sort of filtration you can imagine, and adults are known to jump from one tank to another. Tilapia like Nile and Horonorum need hundreds of gallons of water to spawn reliably.

Just about every commercial grower that has tried to keep 2 species on the same property has failed after just a few generations due to cross contamination.

[Brier]

Digging up an old thread here. Almost all agriculture is compartmentalized. Some farms run cow calf herds, that produce calves, some farms run stockers, and grow them from calves to feedlot size, and some run feedlots that grow them to slaughter. Aquaculture is not much different. You have hatcheries, and grow out facilities. It seems that few want to do both. The growout facilities want fast growing easy fish. The hatcheries cater to this. The backyard aquaculturist, if he wants to produce a superior product ends up having to do both. Overall this may be less efficient, and less cost effective, but if you develop a niche market, people will pay more for a fish that is nothing but a fish. And yes, I agree stay away from hybrids, unless you plan to go back to your supplier regularly, and purchase your next batch of stockers.

[jackalope]

i played with mossambicas for the aquarium industry in '72-75. no market, but they were extremely intelligent fish that were easy to train to thump a device to get food and to run mazes.

I remember them in Salt Lake City, Utah as "African Mouthbrooders" from Redwood Road Nursery in the '60's and '70's .... they were really a Tilapia sold under the scientific name as 'Saratherodon Mossambica' or 'S. Aureus' and 'S. Nilotica' ...... they were "just a different variant" of a Cichlid as far as we were concerned. Now that they have changed to be a 'sportfish,' or 'foodfish' many states won't allow them to be raised, because they want everything to be GMO'ed or hybridized . Monsanto and ConAgra have a very big hold on our politicians, as well as the FDA and USDA.

[jackalope]

The backyard aquaculturist, if he wants to produce a superior product ends up having to do both. Overall this may be less efficient, and less cost effective, but if you develop a niche market, people will pay more for a fish that is nothing but a fish. And yes, I agree stay away from hybrids, unless you plan to go back to your supplier regularly, and purchase your next batch of stockers.

100% agreement here!

[badflash]

A colony of 1 male and 5 females will last nearly 10 years. Not a huge investment for a lot of fast growing fish.

Still, the simplicity of just raising a single sprecies like O. mossambicus is really appealing.

[Brier]

That is a good point, up until you lose a male, and can't replace him with any of your junk hybrid offspring.
Hybrids surely are not a sustainable resource for small scale aquaculturists. Unless you are the guy in Florida selling hybrid colonies for $350 a pop.