Hi all, I've a total 45 fish in my 2.5ft tank which is set up some 5 weeks ago. But in these past 3 days (including today), 7 fish has died (1 neon tetra, 1 black neon, 1 zebra danio, 2 guppies, 1 cherry barb & 1 ballon molly). Another guppy is dying too. I do weekly or fortnightly water changed (abt 30%). The last change was on last Sat. I started to feed the fish with frozen dried worms (in can) on Tuesday & the last time I added new fish (2 black neons & 2 molly) to the tank is on Tuesday & the 7 fish started dying on Wednesday (of course previously there were also fish died but the rate is not that high & close to each other). Does anyone know what seems to be the problem??