I bought five clown loaches around 3-4 weeks ago. I didn't look properly, but when I took them home and put them in the tank, two of them had whitespot. I treated them with esha exit, and made sure I finished the course properly, with putting the temp up aswell. I had to re treat a second time becoz the whitespot would not go. They all looked fine, brightly coloured. Then abotu a week after running carbon throught the tank (after the first treatment I did a water change followed by second treatment) two of the loaches died. I noticed the other three left were looking weak, so I tested the water. Since I first put them in the tank and until now, the tests have always been the same (0 ammonia, o nitrite probably 5 nitrate which i would bring back to zero with a water change and pH always either 7.5 or 7.8) Now, today, two of the loaches I found dead, under rocks in the tank and the third one no where to be seen. They looked fine, eating well and active, very colourful - no fast breathing nothing. what on earth is happening to my loaches? Tested the water again, all parameters the same. Ammonia zero, nitrite 0, nitrate 0. They are in a 400L tank which houses a gold nugget, two guppies and 6 small angels and 1 baby bronze cory.All of them are fine - eating well, healthy etc.any ideas?