Betta Fish and Algae Eater

Question
My daughter bought a 2 gallon tank 4 months ago.  She got a betta fish and algae eater to go in it.  They did fine together and acted like they didn't even know the other was in the same tank.  My nephew came over and knocked hard on the tank.  After he left the betta fish stopped eating and died a week later.  Do you think the knocking on the tank had anyhing to do with his death?

One more question.  We went yesterday to the pet store and bought another betta fish.  He seems to be doing great except I have noticed several times today that he gets all puffed up and then goes and nips at the algae eater.  The algae eater gets scared and swims to another spot.  The betta will wait awhile and then go after him again.  Is there a way we can get him to stop bothering the algae eater?  Why is he bothering him when the pet stores said that wouldn't be a problem?  We're feeling sorry for the algae eater and want to solve the problem.

Thanks.

Answer
Hi Christie;

Poor little guy. The first betta may have bumped himself quickly when the tank was hit and caused internal injury. It could easily take several days for an injured fish to finally die in that case.

Bettas are very terretorial so your new one is just trying to get rid of the algae eater. He is "flaring" to look bigger and try to intimidate him to move out. He is just being a male betta so it's normal. You can try putting a mirror close to his tank for him to get crazy with. He will think it's another betta. Hopefully it will give the algae eater a break.

Most algae eaters get way too large for a 2 gallon tank. Do you know what kind it is? I would hate to see the tank get overcrowded from algae eater growing and one of them get sick and die because of it. Let me know what he looks like if you aren't sure. Otocinclus algae eaters stay very small so they are the only ones that will work out in there. Regular chinese algae eaters get very mean and big and plecostamus get way too large, like up to 12 inches or more depending on the type. Anyway, let me know.....  

At Your Service;
Chris Robbins