I would say the best solution is to get a 5 gallon for the Betta by himself or with a snail or a couple of very peaceable little Otocinclus catfish. That is the best, now let's see what else is possible. Loaches and Bettas are not a happy mix. So I guess if there is someone who has an idea about keeping them in the same tank, let us know. I spent some time here researching and just cannot come up with a happy solution to the same tank question. but i have not owned Loaches before and there may be a trick to them that I am not aware of. In the mean time (I cannot believe I am going to say this) is there any type of temporary quarters you can put the Betta into? He will be fine alone and probably prefer it to being bullied. The only thing is that eventually he will need to be in a tank with full set-up (filter and heater). He can probably live in something smaller for a SHORT period of time without a proper hook-up but be aware that this means much more frequent maintenance and since there would be no filter probably,
ammonia WILL build up no matter what. This means you need to test for the Ammonia,
nitrite, and
nitrate levels in the water probably twice a day in a small tank or container (the smaller you go the more fragile the situation becomes) without a filter and do water changes with TREATED water on a very frequent basis. You do not need to worry about disturbing the
nitrogen cycle because without a filter there is no Nitrogen Cycle. Just testing and water changes - frequently.
I am happy to have met you. Wish it was under better circumstances. Welcome to Fishlore.com. We will try our best to help you and see your little guy safe and happy.
Rose