Help, 2 bala sharks died.

[Jimlor123]

Have a well established 420 litre tropical tank with a variety of fish...
Bolivian rams
3 spot gourami
Mollies
Platies
Paki loach
Turquoise rainbows
Bn Pleco
Gold barbs
And one angel fish
Bala shark

Upon looking in tank this morning my two Bala sharks were dead.....
Everything else is fine..
Water is fine, done test..
Everything is zero, nitrates 4.

Why are they dead??????

 

[melosu58]

Moved to the FW unhealthy fish forum

 

[Flossie]

Did you just add them?

 

[Jimlor123]

Did you just add them?

No I had them for around 6 months

 

[jlk]

Did you check your ph as well? I am honestly not sure what happened. Did they (dead fish) look at all different or unusual? Have you added anything new recently (substrate plants fish)? I am sorry about your fish