Just put my fish in a new aquarium

[Ariamus]

Alll,

I set up a 75 gallon tank last month and I cycled it with a filter from my existing tank, some substrate from the same, and some natural plants. The other day, I finally added my fish and the fish are doing something really strange. They're opening and closing their mouths very rapidly as if they're gasping for air and, for the life of me, I can't imagine the tank having a lack of oxygen. Still, they keep doing it and today, I had my first casualty. Can someone give me hand regarding what this could possibly be?

 

[patagonia]

did u test ur water???

 

[Devilishturtles]

You could have subjected them to either a temperature shock or pH shock when you added them. How did you acclimate?

Your ammonia or nitrite levels could be elevated also, and this would cause problems as well. Do a good water test.

HTH

 

[Ariamus]

Forgot to add that I did, indeed, test the water...pH was 6.2, Nitrite and Ammonia levels were nil, and general and carbonate hardness were both in the 1-2 degree range. All in all, excellent conditions for the type of fish. pH shock seems like the most plausible theory as I did not test the pH in the smaller tank before the switch but the last time I tested it about a month ago, it was about neutral.

At any rate, I added a stress coat product and put in a bubble maker in the aquarium to circulate the surface a little bit more and it seems to be doing the trick. The fish aren't as agitated. In fact, all my Black Ruby Barbs have stopped the strange behaviour and their deep colors are returning. And, my remaining Tiger Barbs seem to be coming around too.

Thank you guys for the help.