Originally Posted by chrisfoerst
What's your pH and temp?
Blue Tilapia have a 96h LC50 of 14 ppm to 19 ppm (mg/L) at 8 pH and 73 degrees Fahrenheit. Unless you raise it passed 4 ppm ammonia to cycle your system, the levels will not be high enough to kill most of your fish! To be safe, don't put fish in if you started the cycle with more than 2-3 ppm ammonia.
As a side note, I would put my feeder goldfish in no matter WHAT the conditions. The real men will survive, and Darwin will have a happy school of soldiers to carry on the aquaponic legacy!!!
REFERENCES
Palachek, R. M., and J. R. Tomasso. 1984. Toxicity of nitrite to channel catfish (Ictalurus punctatus), tilapia (Tilapia aurea), and largemouth bass (Micropterus salmoides): evidence for a nitrite exclusion mechanism. Canadian Journal of Fisheries and Aquatic Sciences 41:1739-1744.