How should I take care of a cut on a fish?

The water was being changed and the fish jumped out and got cut pretty bad... What can i do to try and take care of the wound? It is a beta fish

Suggesting that someone flush a live fish is disgusting and appalling. Fish feel pain, just as all living creatures do. The price you pay for a creature doesn't determine the value of it's life.

As already stated, pristine water with a medicinal dose of aquarium salt (one teaspoon per gallon) is your best bet. If you start to see signs of infection, you may need to treat with antibiotics. You MUST be careful with products like Bettafix and Melafix, as these have been known to cause damage to the labyrinth organ (breathing organ) and delicates fins of bettas. If you do use it, use 25% of the recommended dose.

a cut? as in bleeding? or white specks? we have saltwater fishes and they had these white "stuff" on the them...which was actually a sickness and you need to add chemicals to the water in order to treat them....sorry, no suggestions about the "cut" though.

Lots of water changes, and add a bit of aquarium salt.

How long was he out of the water? He may not survive if it was long enough for him to be cut up badly.

EDIT: Do NOT flush a live fish down the toilet. It's incredibly inhumane. There are ways to humanely euthanize fish out there - and that is NOT one of them.

Flush it down the toilet and get a new one. Betta fish are only $3 each, so it isn't worth the effort to try and remedy the problem.

There is a medicine for betta,It will help heal the cut.I used it on my betta and it worked perfectly,It is called betta fix,But even after medicine is givin must keep your eye on it.

add some rock salt to the water and pour a bit of Stress Coat onto the fish in might be ok

Years ago I used to work for a tropical fish importer/wholesaler. When we had injured fish like that, we used superglue. Believe it or not, superglue is an effective fish band-aid. Don't worry about getting it off later. As the wound heals, it will come off on its own and will be caught in the filter.

Catch the fish out and place him on a wet piece of cloth. Paint the wound with the superglue, (don't use a Q-tip or anything that will leave lint, if you are careful, the long edge of a toothpick will do.) let it dry a bit, just so the top has a skin and is sort of tacky to the touch, then return him to the tank and turn the lights out to calm him.

Hope this helps