I've got a problem. My little tilapia fingerlings have been dying off one at a time every since I put them in my tank. Lose about one or two a week. There's hardly a trace of ammonia or nitrite in my tank. I'm suspecting it's the nitrate levels, which are pretty high. I've been working on doing partial water changes to get that nitrate level down. Its at around 80-100ppm. . It skyrocketed after I added maxicrop to my water 3 or 4 weeks before I even got the fish. It's been tough for me to do proper water changes because my water is so high (pH of about 8) and it's winter, so I don't have access to fresh rain water. Right now, I have to pump it to a 50 gallon drum, make pH adjustments, and then pump it into my tank. Symptoms: I notice that one fingerling will get a little "woozy" and hang out at the bottom of the tank. Usually the next morning they'll be dead. I managed to pull one out of the water and he seemed far from vigorous. I'll keep up with the water changes. In the meantime I wanted to ask: how much nitrate does it take to compromise the health of a tilapia fingerling? Is nitrate even the issue, or do I have some kind of disease in my water?
That describes it pretty well. Although, I'm not sure they actually are touching the bottom when they flip. I haven't noticed anything upon examining the fingerlings, but I don't have a lot of experience with identifying problems with aquatic life. In fact, I have none :)