what is wrong with my betta's fin?

[chentillo708]

My betta's fin looks torn and I don't know why. He spreads his fins a lot because he is a little aggressive. If anybody can help me thank you.

 

[Colin_T]

Hi and welcome to the forum

How long has the tank been set up for?
How long have you had the fish?

Have you tested the water for ammonia, nitrite, nitrate & pH?
If yes, what are the results in numbers?

What sort of filter is on the tank?
How often and how do you clean the filter?
Is the filter run all the time?

How often do you do water changes and clean the gravel, and how much water do you change?

 

[chentillo708]

Hi and welcome to the forum

How long has the tank been set up for?
How long have you had the fish?

Have you tested the water for ammonia, nitrite, nitrate & pH?
If yes, what are the results in numbers?

What sort of filter is on the tank?
How often and how do you clean the filter?
Is the filter run all the time?

How often do you do water changes and clean the gravel, and how much water do you change?

The tank has been set up for more than two weeks. I’ve had the fish about the same time. I have not tested the water. The filter runs all the time. I haven’t changed the water since it has not gotten dirty.

 

[Colin_T]

If the aquarium has only been set up for a couple of weeks, then you probably have ammonia in the water that is damaging the fish's fins and gills.

Basically anything that breaks down in the water (fish food, fish waste, dead plants, etc) produces ammonia. This is normally broken down by beneficial filter bacteria. However, it takes about 4-5 weeks before the filter develops these good bacteria and until that time, you get ammonia and nitrite in the water and that harms the fish.

If you take a glass full of tank water to a pet shop, they might test it for you. Some shops charge a small fee for this and others don't. But if you do get the water tested, ask them to test for ammonia, nitrite, nitrate and pH. Write down the results (in numbers) when they do the test and post the results here. The results will read something like the following: Ammonia 0.25; Nitrite 0.5; Nitrate 25; pH 6.8.

In the mean time, I would suggest doing a 75% water change and gravel clean the substrate each day until you have the water tested. If you don't have a gravel cleaner, you can get a basic model (like the one in the following link) from any pet shop and use it to clean the gunk out of the gravel without moving the fish.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
https://www.about-goldfish.com/aquarium-cleaning.html

You are doing a fish in cycle, which means you have fish in the aquarium while the filters develop the good bacteria. You should only feed once every second day and do a big water change each day to dilute any ammonia or nitrite in the water. You should do this until the filters are capable of removing the ammonia and nitrite. There is more information about filter cycling at the following link.
http://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/