gloomy day in my aquarium :(

[alesserfate]

So everything was well, our happy fire shrimp, mimic tang, bublebee snails and emeraldcrab lived happily in our tank. We added a baby cromis and one grown engineering goby. Next day mimic tang and cromis are dead. Bad move?

[JTang]

Sorry bout the loss! Hope the rest of them r fine...

[gklaw]

Sorry to hear that. There may be other reason than the new fish. Temperature, etc.

[SeaHorse_Fanatic]

What size is the tank?

Any other possible causes?

[alesserfate]

Its a 40gal, temp was ok. I know the alkaline level was a little bit low so maybe it was hard for them to breathe with more fish per volume, but I've sorted it out and bought some new fish so hopefully all is well to come!

[whatigot]

With those fish in such a small system, I would bet there was some significant aggression that resulted in these deaths...

[mcrocker]

Check this out: Engineer Goby..The killer - 3reef Forums

I wasn't familiar with an engineer goby so I googled it, and one of the first results was referring to a goby possibly killing chromis! I'm no expert on these fish, but this sounds like a similar situation.