Hi. I have some Apistogrammas in my tank (150 gallon approx). It is Pucallpaensis and Agassisi. I have had the pucallpaensis for three months and since two weeks ago they have started to die off. First they spin around chasing their rear fin like a silly dog. Then they tire and lie flat on the side and death occurs with the hour. What is this? What can I do about it. I thought it was some kind of poison so last week I changed 80% of the water to reverse osmosis water and added some salt. But today I will loose another fish again it seems. Help!:frown: