Bump on Betta???

[versacesuicide]

Hi, so I'm new to bettas/fish keeping in general but I have 3 bettas all in a 5.5 gallon and one of the tanks was a different 5.5 and came with a stronger filter suitable for 10G tanks but my fish doesn't like it so I ended up buying a 3G tank filter and he likes it much better. Just now I finished feeding my fish and noticed he has a large bump under his gills/where his ventral fins are attached to and I'm really concerned about him and I've seen other people say this could be because of ammonia poisoning and not enough water changes but I set up his tank last week, he's doing fine and is swimming and acting like he normally does so I thought maybe the filter could be the problem? If anyone has any info about what I should do pls let me know, thanks!

 

[versacesuicide]

Hi, so I'm new to bettas/fish keeping in general but I have 3 bettas all in a 5.5 gallon and one of the tanks was a different 5.5 and came with a stronger filter suitable for 10G tanks but my fish doesn't like it so I ended up buying a 3G tank filter and he likes it much better. Just now I finished feeding my fish and noticed he has a large bump under his gills/where his ventral fins are attached to and I'm really concerned about him and I've seen other people say this could be because of ammonia poisoning and not enough water changes but I set up his tank last week, he's doing fine and is swimming and acting like he normally does so I thought maybe the filter could be the problem? If anyone has any info about what I should do pls let me know, thanks!

update: I think I just may have overfed my betta

 

[Colin_T]

Hi and welcome to the forum

if you can post a picture of the fish we will have more idea of what is going on

 

[HoneyGourami]

Please post pictures.

Three bettas in a 5.5gallon is a very overstocked tank. The minimum for a betta is 2.5gallons, but for a plakat betta it should be atleast 5gallons.
If your bettas are not plakats you should separate your bettas, because if you don't have them separate they will eventually kill each other.

Female bettas do get along, but for a sorority, they should be kept in a 20gallon tank minimum. You can divide this tank for an easy fix of space, and each betta can get 2.5gallons of space.
For the third betta, get another 5gallon, or 2.5gallon from your local petstore.

The filter is not the problem here, only if he gets sucked, and stuck on the intake. If it is pushing him a little, it's just fine. Too much push may be a bother, but not the cause of this.
It may be a tumor, but he would not be able to swim well if it was, so if you are not noticing swimming issues it must not be a tumor, it also may be a bloat.

If it is a bloat, do not feed him for a few days, and then try a de-shelled pea after about four days, and that should fix his bloated tummy.