They hate bright light. They could do o.k. in a 55 if they have a large enough cave to live in. That said, the smallest I kept one in is a 125. He'd come out everyday when I walked in the door from work and greet me then go back into his cave away from the lights.
All of my Marine Bettas were raised on TDO. Even all my wild caught ones take TDO and come begging for food when they see me.
I have singles in 20 gallon tanks without problems. 55 gallon is definitely sufficient as long as you have enough caves and overhangs.
C. argus is the single one.
What tankmates would you suggest in a reef type setup I’ve been considering building a 120 and getting a harem of marine Betta but am not entirely sure what would work well with them
With mine, I have many tangs, clowns, trigger, copperband butterfly , anthias and more
What would be comprising the and more
I would avoid any with aggression as you likely know, bettas are very peaceful and non-conflicting in a tank setting
I’ve been trying to plan my stocking to work with that best I can with a few yellowfin flasher wrasse, a school of lyretail anthias, a couple spotted croucher gobies when the corals throughly established, a school of blue chromis potentially, and a few royal grammas and not the dottyback. As well as considering a tropical abalone as a cool cleaner snail, also considering a few clowns as well because I was worried they could be eaten and marked them as unsafe in the presence of a betta.
Anthias as with mine should be quite safe
I would just get a wild caught one they are wayyy cheaper and you can get them at a decent size. Captive bred ones are like 3 inches max from all captive bred places.
If you click on my build thread and follow the Reef Inhabitants link you can see what fish currently reside with my betta (including past fish no longer with me that also got along).
