Bettas can be aggressive to other fish, however not always. It might be your fished rammed up against a decoration.

Clean water is the key for wounds. Water temp is too low. Should be higher for the betta. Raise the temp up to 79 at least.

You can treat the tank with a general antibiotic, but if you do this, realize you then kill all the bacteria - both good and bad.

Just do water changes to keep the water as clean as possible. Fish have a mucous that covers their bodies to help keep bacteria at bay.

Thank you, I try to keep my water clean as possible anyway, so I'll keep doing that.

But isn't 79 too high for my other fish?

I really don't think it was my betta because he's completely apathetic towards the smaller fish, and his mouth seems too big to have made the marks. The only time he's ever been even a little agressive was when he discovered algae wafers for the first time, and he was trying to figure out what the heck it was. But he only gently nosed them away then.

Kitty asked:Would adjusting the tank to any particular temperature be helpful? (I keep it around 74 F.) Skygee replied: Water temp is too low. Should be higher for the betta. Raise the temp up to 79 at least I agree with Skygee if your tank is cycled allready. If you are still in the begining stages where ammonia is still detectable a slightly lower water temp. is best. Ammonia is more toxic at higher temps and pH. Here is a free calculator to determine ammonia toxicity. Since you are cycling the neon may have ammonia poisoning and the "wound" is from loss of slime coat from stress. Ammonia poisoning also creates red streaks on fish. Neon tetras are delicate. With that said the amount of fish you have (1 white cloud, 1 glowlight tetra and 4 neon tetras) could also be an issue. They are nippy fish to each other sometimes, that is why schools of 8 or more of each of these fish is desireable. Also the white cloud is really a cool water fish and can be kept in an unheated tank. They are OK in tropical tanks also but temps 60F-72 are optimum.

Here is a link that might be useful: free ammonia calculator

Check the link below and also hit the toxicity for ammonia article link within it.

Here is a link that might be useful: FAQ: beginners the nitrogen cycle, from

Thanks for the links. It turns out that it was my glowlight. He started picking on the other fish for some reason, probably because he's bigger, said the fish store lady. So I traded him in for a neon, and all is well. My injured one has been acting perfectly normal, so I think she'll heal just fine. =^_^=

Thats good, when the tank is established (cycling) get a few more neons, they don't add much to the bioload and 8 or more is better. Good Luck.