why

I woke up this morning to find all 4 of my tiger barbs dead.  Anyone have any thoughts of why?   55 gallon tank cycled for 3 weeks before adding fish have had fish in the tank for just over 4 months now 2 of the tiger barbs that died were of the first several fish I had populated the tank with...

My black molly of a week liked playing in the tank, last evening he buried his head in the rocks on the bottom of the tank and died, anyone have an idea why?

Hi All Since swapping over to sand a few months ago , my bottom dwellers started to flick and still do. There has been no ick or signs of ulcers or anything else. I treated for internal parisites awhile ago for my guppies as not sure if there was a problem there , but they are ok . It is just my...