[Sena Hansler]

Don't change the filter!! I know some filter cartridges say "change after a month" but it's their way to steal your money. That filter cartridge has the beneficial bacteria, that keeps your tank cycled (if it is cycled), or helps it to cycle. When you do a water change just give it a swish in the old tank water.

How often do you clean the tank?
How much of the water do you take out during a water change?
What do you add during/after a water change?
What temperature is the tank?
What else is in the tank (fish, decor)?
What do you feed him and how much does he eat?

And do you have a picture of him?

 

[Sena Hansler]

It could heal right away, if it was just damaged from decor. Plastic plants can do it, even when you don't think so... I haven't seen "pin holes" or tears from decor, since only using silk, silicone and live plants. Test the plastic plants... Run a piece of pantyhose on them, and if the pantyhose tears or runs.... Your fish's fins can tear as well.

Change the filter cartridge when it is falling apart... Or once a year. That's all you really need to do It might look "gross" but it's supposed to be that way lol. Just remove any algae or build up.