All the fish I get, grow well, are healthy and never give me problems. My clown loaches are a different story. Water parameters are excellent, I have over filtration to the max, and do 50 percent water changes every week. I have a small shoal in my planted 60 gallon,they are about 5 to 6 cm big. they all seem healthy active and eat well. Slowly one gets thinner and less active, and dies. The others all fine. A week or two later, one gets slowly thinner and less active, then dies. The others all fine fat and healthy, then slowly a week or two later, one gets slowly thinner and less active and dies. The others all healthy. This trend continues. Right now I have two healthy clowns left, and the third is now thin and less active. All my other fish in the tank are healthy and never exhibit this behaviour