Hello
I recently purchased a new little crown tail beta and had a few questions about him. For background info i have had him a week now and he was bought with 2 oto catfish. Before purchasing him i read this forum for a few days trying to learn what he needed. He is currently living in a 10g tank with a heater that keeps it 78 and some silk plants for looks

. He has also taken to blowing bubbles all around the top of the cage, which i am taking as a good sign from what i have read.
My first question was kinda related to the catfish. I purchased them to help keep the waste down between cleanings ( i plan on doing a 50% water change once a week, unless it looks like it needs it more often). I intended on buying a plecostomus (this is what we always had as kids) but the owner of the pet store advised me that the oto might be a better choice as thats what she used. She said that two for a 10g tank would work well.
Now here is where my problem comes in. The oto were fine this morning and then about 2 hours ago i went up and they were both dead. I have been reading about them since then and believe their death was due to the fact that they didnt have enough algae to eat. This was my fault as i believed that they would eat "anything" like the lady said and therefore would eat the beta food that my boy didnt.
So i am now left with one very tiny beta (hes probably only about an inch and half long max) who seems to be happy enough but nothing else. I read that i could supplement the oto's diet with either algae blocks or fresh veggies but didnt want to buy another oto and start feeding it these things if they will hurt the beta? Would you even recommend getting an algae cleaner fish to begin with? If not i have read there are a few other species of fish that you can pair with the beta without them fighting, would you recommend any of them to a new owner?
And my last but not least question is this. I was at the store a few days ago and saw that about 5 of their 15 beta's were dead and the others looking like they were on deaths door. Having a huge heart ( and an extra 10g tank and gravel) I bought one that looked in dire need and brought him home. Since having been put in clean water and getting warmed up he to started to blow air bubbles this morning. I have read online that you can put 2 males betas together in a tank if there is a tank divider. Is this possible or should i just let them live out their lives in 2 seperate tanks? The reason i ask is that they look lonely in those big tanks all by themselves.
And if you are still reading this i thank you very very much for your time. I know its a lot of words but i wanted to give as much info about my setup and questions as possible from the beginning. Any tips and/or constructive critism on my new boys keep is welcome.
Thank you again