[bartian]

Paros and coccina-group bettas are the perfect match, if one wants keep paros with other fish for whatever reason. I do combine my bettas with bigger, stronger paros like quindecim[i] and [i]bintan.
However, I think 30 liter is way to small for this combination or for multiple males! The extra stress caused by lack of space will harm them or increase aggression. I’d recommend not keeping Betta in tanks smaller than 60cm (54L), especially when keeping two or more males.