Cory with a broken fin?

Question
I bought my daughter three corys two days ago. We also have a male Betta and a Dwarf African Frog. Up until tonight they were all o.k. When we checked on them tonight one looks like it has a broken fin, the right one behind the gills. The Cory keeps swimming at the top of the tank and is not moving that fin at all. It seems to try to swim to the bottom but is having trouble. What should we do and will it heal on it's own?

Answer
Dear Julie,
Many fish can get their fins broken or torn. Often the most common reason for this is when they get netted out at the petstore, nets can be really hard on fish, their fins do tear easily. But fortunately it usually doesn't do them too much harm at all. And most all fish can heal torn fins in a matter of days. An important thing to remember though is to keep their water clean and the gravel bed clean as well. If the aquarium they are living in is very dirty, bacteria can infect the broken or torn fin and cause an infection. Of course, an easy way to prevent this is by doing frequent partial water changes. Use a aquarium gravel siphon/vacumm and make sure to siphon out all organic material in the gravel bed.
The frequency of these partial water changes depends on the size of your aquarium and of course the occupants within. Something like a 10-gallon aquarium with a Betta, Dwarf Frog and Three Cories could do well on twice a week water changes. Something around 20-30% the larger and more frequent water changes, the better. Fish thrive on water changes. (But always make sure your replacement water is equal in temperature to that of your aquarium and insure it is dechlorinated everytime with a good water conditioner)

The one Cory with the torn fin's behavior of swimming to the top of the aquarium from time to time is considered natural cory behavior. They take occasional gulps of air from the surface in a quick dash to the top and then they quickly swim back to the bottom. But when your cory does these surface visits excessively, this may mean that the water is low in oxygen or it may be polluted.

Make sure you have a good filter on your aquarium. The best all around kind are the hang-on-the-back Power filters. I have found these types of filters to be the most efficient and easiest to maintain filter around. Sometimes these power filters can create too much rough current for a docile-swimming male Betta. So to help keep him comfortable, some filters have a flow control on them. But I have found it's best to position plastic aquarium plants in front of the output of the filter to diffuse and slow the current down.

Your Cory should be fine and certainly will heal his broken fin on his own. But please make sure that poor water quality isn't causing his behavior of constantly swimming to the top.

I really hope this helps and if you need anymore help, feel free to write!

Karen~