what to do about rosy barb?

[msp75]

I had a pair of rosy barbs, but one died several days ago. Since then, the other one has been swimming rapidly up, down and around the tank. I don't really want to get another rosy barb, as they get a little large for the tank I have (only 5 gallons) and are aggressive with the other fish, but I feel like I should because of this one's strange behavior. I will get another one if it will make this fish more comfortable/happy, but I'm not sure of the reason for his behavior. Is it because he's no longer part of a pair, and is this something that will subside or do I need to get another one to keep him happy? Thanks in advance for any advice!

 

[TKOS]

See if you can trade it in at your local fish store, you might be able to get a more appropriate fish for your tank size, Bettas gouramis and paradise fish will do well in smaller tanks (not all together of course). Rosy Barbs need to be kept in groups of 5 or more really to keep aggression down and really need at least a 30 gallon tank or more.