I cannot figure out what is wrong with my male betta. I had him for 3+ years and I got him as an adult, so I don't know how old he is. His dorsal fin has been missing from day one. Not sure if it was a filter accident or fight or whatever. Over the past few days he has been very inactive. He stays at the top in a back corner, sometimes even lying on his side. He comes to to eat and still has appetite but then he goes back in his corner. He is in a 10 gal tank, nitrite 0, ph 7.2, nitrate 5.0, amonia 0. he gets weekly water changes. Hikari betta food. aquatech 10 gal filter. I see no visible signs of any lesions, fungus, swelling, etc. Any suggestions?

I cannot report on poop color/consistency since I have never seen him poop.

I've seen this with a lot of bettas at my work. Normally it is either temperature related, bacterial infection or parasites.

A couple of questions-

1. Do you have a heater? If so, what temperature is the tank at?
2. Do you have any pictures you can post of him?
3. How much are you feeding him daily?
4. Any raised scales or missing scales? Odd looking gills? Stringy clear thread-like structures hanging from any part of the body or tail?

You mentioned that you got him when he was an adult. Another possibility might be to consider that his age is a factor of this. He could just be an old man and developing some issues.

Either way, I hope he turns okay!

Sorry, can't post a pic at this time. Camera is not doing right. I can't see rasied scales, missing scales, or any stringy material. He just looks like his regular self, just not acting right. I don't have a heater. Temperature is around 76/77. I feed him about 3 little pellets a day. I have also considered that he may just be old.

Well, nothing has changed. I took him out to take a closer look and I can't see any obvious signs of any disease, fungus, ick, velvet disease, growths, lumps on the body. Just really nothing. He still hangs out in a corner but he eats and seems otherwise OK.

mabie he is just being an old gezzer...

I hope you find the problem..

I have been reading a lot about betta and I guess the average life span is 2-3 years. Since I had him for abou 3 years I guess that does make him a pretty old man. I know I'll miss him dearly when he passes on. He is on my desk and used to watch me all day long while I work on my computer. I guess time will tell....

Well, he is not lying on his side anymore. He has been upright since yesterday, still eating normally. I tried to give him a bloodworm for some variety, but he would not take it. He ocassionally swims just a little bit, but basically stays in his corner. At least he is not worse. I wish I could do something for my dear friend.

I had an elderly betta who had some of the same symptoms. he was 3 1/2 years old . I was chalking it up to old age but I tried adding a heater , salt and melafix and he started eating again and acting normal. Have you tried looking at him with a flash light up close. Sometimes velvet is very hard to see. It presents itself as small gold dust on fish. I think my older betta had velvet .

Yes, I have done that. I had a fish with velvet before. He definitely shows no signs.