Fish Behavior Disaster - PHOTO included

[Pipa]

In my 18 gallon tank I have had 2 cory catfish, 1 barb, and 2 zebra danios. Yesterday we added an Australian Rainbowfish (nearly same size as barb), and from moment one the barb attacked. We have 1 barb because our other one died a couple months ago and we never replaced him. So this one has been king in the tank for some time. Anyway, we noticed the rainbowfish acting a little lethargic last night, and since we dont have a quarantine we seperated him from the barb by putting him in a large bag full of the aquarium water with a small air hose to give him aeration. This morning I can see that his fins are shredded and his eyes have some whitish stuff on them (see photo). I dont know if its from damage or disease. We really dont know what to do, Im afraid of the barb picking on him to death (literally), or we are faced with taking him back. Will this barb ever allow anyone else in the tank? We had 2 platys for a little bit and he didnt bother them, and he rarely cares about the others as well. I dont know whats different about this new one. He's a meanie!

 

[Pipa]

Photo:

 

[Menagerie]

The rainbow became stressed and this is what happens to a VERY stressed fish.

I dont know if its from damage or disease.

This is the result of damage and then the fish's immune system looses it. Fins fray and the eyes go cloudy. Unfortunately, I have seen this before with my African cichlid tank. This fish needs to be treated immediately. I suggest using both Melafix and a kanamycin based med. However, it may be too late for this fish. I had found that once they get to this stage, they do not bounce back.

Will this barb ever allow anyone else in the tank? We had 2 platys for a little bit and he didnt bother them, and he rarely cares about the others as well. I dont know whats different about this new one. He's a meanie!

The barb probably decided that the rainbow looked to similar to himself and was a threat.

Since the barb leaves the danios and cories alone, I would add more of them. Both the cories and danios like to be in groups of 3+. The barb might like more friends, but I'm not sure how he will react to more of his own kind.

 

[Pipa]

We took the rainbow back. It just wasnt going to work. We got 2 buenos aires tetras instead. Their tank seemed healthy and they seemed more able to defend themselves than the peaceful rainbow. He was just too docile. There has been a lot of chasing, but now the barb has 2 to deal with and there has been far less actual nipping than with the rainbow. I'm not sure how it will work though....I guess only a few more days time will tell. . .

 

[Menagerie]

The tetras also kind to be in groups of 3+. I would get at least one more tetra to spread out the aggression.

 

[FawnN]

All the fish you have chosen are shoaling fish and need to be in larger groups. Tiger barbs are the most aggressive out of all the barbs and will nip and harass all the fish they can if not in a school of at least 4+ and you will continue to run into these problems if you don't increase your barbs.

I personally would get rid of your barb and increase your cory's and tetra's and whatever else you want.

I have an awesome school of 9 zebra's and they bring so much activity to my tank and are so much fun to watch.

I personally think you should get rid of the barb, add 2 more cory's, add 4 more zebra danios and 2 more buenos aires tetra's. And remember to keep up with your water changes because tetra's can be a little sensitive to changing water conditions.

 

[TankGirl]

I think some of the trouble is related to the relativley small confines of an 18gal. You need to get the numbers up to spread out aggression, no question, but this is a small tank so stock very carefully. If the tetras don't work out, then get more barbs and stick to one "feature" school of fish and resist the urge to have one or two of several species in there. I do think a few more cory cats would be good for them, though.

 

[Pipa]

Well the 2 Buanos Aires Tetras seem to be doing well - and much better than the rainbowfish. There is still some chasing, but they hardley ever make contact to nip, and I have even seen the rosy barb and the tetra's exhibiting schooling behavior. I think it will work out fine....every day I have seen improvement. Thanks for all the advice!