What would cause this?

[Trilogy]

Have a 10 gal tank running for 2 months now. It had 4 tiger barbs in it. I added a panda cory and the barbs were picking on it so much that I took it back and got another tiger barb that same night. 5 days later the new tiger barb is swimming in spirals around the tank. I had to work so there was nothing I could do at the time. When I got home that night it was just as I expected. He was floating near the filter intake. There wasn't any visible signs of disease. I tested the water before adding him and had 0 ammonia and 0 nitrite. Any idea of the cause?

 

[Caspar]

How was the Barb acclimated to the tank. I may be grasping at straws here but it could be osmotic stress.

 

[afishyonados]

A couple of really well placed body shots bay the pre-existing barbs could have that effect.

 

[Trilogy]

I put the bag in the tank and slowly add tank water to bag for about 30 minutes before releasing to the tank.

 

[Cinder]

I agree that the most likely scenario is the original Barbs attacking the new addition. It is also possible that it had a problem prior to your purchasing it.
Just some information for you. Tiger Barbs are very active fish and are also shoaling fish. Thus, they should been kept in groups of six or more (more is better) and shouldn't be kept in a tank smaller than a 30 gln. Being in the ten gallon will stress them all as they grow so if you can upgrade to a larger tank you should do it as soon as possible. If you aren't able to then I would suggest you returning the Barbs and finding fish that are more suited to a smaller tank. Good luck.

 

[Asher]

Not to rain on the parade anymore, but those barbs will likely pick on most anything that you add to your small tank from here on out. They can get pretty territorial, especially in a small tank with limited hiding spaces for other fish. I don't know how attached you are to them, but I would agree with cinder. Upgrade (which you still might need to be careful) or return them and get some nicer schooling fish. I have a 10gal fresh (along with a 55) but in that tank I have kept for a while now:

1 red beta
4 zebra danios
8 neon teras
2 sunset platties
1 pleco

I do have alot of filtration on this tank, but there are plenty of options, activity and plenty of color to choose from for what you have.

 

[Trilogy]

Thanks for all the tips. I am aleady planning for a larger tank soon. I have a 4ft wall that is screaming "put it here!". So I am hoping to get a 75gal but like most it comes down to time and money. No I am not attached to them but I do like them and would not get rid of them unless I have to. I had hoped to put them in a larger tank but wasn't sure if they would still be agressive even with more room to run. If they can't get along with others I'll have to give them back. Lets hope not though. I made the mistake of trusting the LFS. I know now to post my list here first to see if they will live hapilly together.

 

[Asher]

just remember to put plenty of plants, rocks, wood, etc. for fish to find cover if they need it! a 75 gal would be awesome!