Betta lethargic and laying on his side..

Hello,

I have not posted in quite a while, but I have an issue and all my web research seems to only pull up answers to aquarium newbs and fishbowl owners, which I am neither.

I have a lovely orange male betta, who lives in a fully cycled, 5-year-running 20-gallon tank, heated, filtered, with lots of plants and decor. He lives with 10 corydoras, 4 cardinal tetras, and a Bolivian Ram. The water parametres are perfect, per my API master test kit and water changes. My betta has lived happily alongside his tankmates for 2 years, and there have been no new additions to the tank in over a year, and I am a fairly experienced tank owner.

However, for the past few weeks, he has been lethargic and mostly laying on his side, either on the bottom of the tank or in one of the plants. He shows no signs of disease, except for trouble moving, almost as if he is having a spinal problem. For the past couple days, he is also breathing a little heavy, but I assumed this is because he is not going to the top for air much, since he is an antabanoid. All of the other fish are fine, eating, swimming, interactive, just my poor betta. I have no idea what to do with him..

I am at a bit of a loss as to what to do, and am starting to consider euthanizing him (humanely, of course, via the freezer method) - I just don't want him to suffer.

Any suggestions?

Bettas can definitely live up to 5 years - this is why I abhor bowls, I want my betta boys to have the best life they can. Sadly, I don't know how old he was when I got him, I just assumed very young, but he was a petsmart rescue, so I guess I have no way of knowing for sure, and he sure did not come from a good quallity of life before..

No lumps that I can tell, just that he seems to twist himself up a little bit, almost makes me wonder if his spine is curved?

As for euthanizing - actually, the freezer method is what I learnt from the AC here, including suggestions from senior members on numerous past posts. Clove Oil is impossible to find here, and I cannot afford to order it online.. so it seems freezing is the next best thing. I have euthanized a distressed dying fish this way before, and it was very quick, out in 1 to 2 seconds.. of course, it's the quick shock method, putting him in almost frozen water after breaking the ice crust on the top.. I know perhaps it's not ideal, but hopefully it's not that bad. It wil be fast.. sad, but fast..

I think this may just be what's in store for tomorrow.. my poor little Alpha.

I know that clove oil does cause less stress.. but per my previous post, it's impossible to find where I live (beleive me, I have looked) and from what I have found online, it would cost more to ship it to me than even the purchase price online, which I just cannot afford.

I ussually have only had my fish die of old age, save for 2 danios that I saved from a laboratory that were in serious distress. I would rather have my fish die of old age, but in this case, I am just concerned that my betta is suffering. 2 seconds of the stress from freezing would possibly be far more humane that days/weeks of suffering in his current state, since I assume he is in distress and I cannot seem to find a cause?

I hope I am doing the right thing..