sudden, random death...

[spennylane]

I have had my tank some months and all the levels are fine (NO2, NO3, Ammonia in particular) tank size 12 x 18 x 18.
I have/had 3 foxes - all healthy, 4 danios - 3 died in last 2 days, 2 platys - 1 died in last 2 days, 4 diamond tetras - introduced 2 days ago - all healthy, 5 neon tetras - introduced 2 days ago - 3 dead, one will be dead by the time I get home.
Strangely the deaths started just before I into'd the new fish - ie they were fine when I went out to get the fsh, when I brought them back the platy had gone.
Also the neon tetras seem to be losing fins and or tails just before dying...
Also what is the best euthenasia method?? (that is a side line)
Thanks..

 

[black angel]

too many fish seems to be whats wrong. in a tank so small you can really only keep a betta. what kind of filtration have you got?

 

[breezer40]

Flying foxes can grow to around 5 ins and from what I have read more than capable of shreading tails

As black angel has already said..too many fish for that small tank.