Aggression

Question
Recently I added a Blue Gourami to my tank and it has been acting normal for just being added into a new environment except that one of the mollies I also have in the tank has been nipping at the gourami's sides.  Whenever the mollie would think I wasn't looking it would go back to nip at the Gourami and I'm not quite sure what I should do about this aggression, could you help me? I have a 29 gallon tank with one betta, three mollies, four Australian rainbowfish, and one gourami.  The filter system is a Topfin 30 and a Penguin 125.  The ph is about 7.2 ammonia is 0 and nitrite is about .25.

Answer
Hi Jane;

Mollies can be a bit nippy at times. The funny thing is, so can blue gouramis! I think it is possible that with the stress of getting a new home and the elevated nitrite level, he is just having a hard time. I would make a partial water change of 25% and measure the nitrites again. Every day that you get a detection of any nitrites, make another 25% change. An established tank should always have a nitrite level of 'zero'. It is very toxic to the fish. Water changes are the best way to lower them. The fresh water is very helpful to the fish for other reasons too. It boosts their metabolism, helps them grow and keeps them thriving.

You will eventually have trouble with the gourami picking on the other fish. Especially the betta. Watch them as he grows and separate the betta if it seems necessary.

It is great that you have two filters on the tank. That really helps. Keep up the good work!

Followups welcome

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Chris Robbins

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