hi - after the demise of my female, i am left with my beautiful male (ice-man) all alone in a 3.7 USgal tank. can i have any companions for him, or should i leave him on his own? i want him to be happy

In a tank that size imo it would be best to keep you betta alone.

Are you keeping this tank cycled? or are you doing 100% water changes and using ammonia detoxifier?

If it is cycled you could add a couple ghost shrimp if you like but the fish may decide he wants a snack

Luke Anderson if my Aquarium is like a 20 gal
do you think it's big enough for 2 bettas?

I know we shouldent put 2 bettas toghther or a other
companion?

As long as you put a divider in, they should be fine. You can fit more than 2 bettas in a 20 gl tank, though....
As for other companions, bettas are very aggressive. Some people say you could put a betta with anything tropical that doesnt have long finnage, but I have seen bettas nibbling on even the strangest of things, including a snail, hanging on the glass....
I even found one of my betta fry eating some smaller fry. It looked kind of funny actually, seing a 1/2 inch betta eating a 1/4 inch betta. All I could see was the tail in his mouth! No mercy, not even from siblings!

yah u dont want to put battas together even male and females.some good company 4 them r guppies(carfule though they do breed alot and can change sexes)yes almoast all tropical fich are good with bettas. just make shure they are non agressive and arnt flash with long fins.

i'm using water changes and ammonia detoxifier, because the tank's not really big enough for a filter. i think i'm going to leave him on his own for now at least. he seems happy and has blown another nest, so it's robably best for me to leave him for the moment at least. thank you!

Thank you