pea puffers are a little challenging to breed and getting their young to survive in the same tank as the parents for any amount of time is challenging. really dense moss or a mop head work well if you use allot. prime time aquatics has a video about breeding them. moss and water volume are the main thing. ive gotten my c irrubesco to breed in a tank with leaf litter and drift wood but they ate their young soon after because while the leaf litter did give really thick and complex structures it still wasnt enough. also make sure you cover your filter with sponge.
my dwarf puffers are in a 20 long with about 40 other fish and do fine but i wouldnt expect them to breed with tank mates. loaches, corys, cypranids, african dwarf frogs, and a hingemouth live with my dwarf puffers and cause very little trouble. they occasionally nip a fish when startled by its quick movements. i would use otos or hillstream loaches instead of a pleco personally.
i didnt want to add plants to my tank but my puffers were very nervous so i found if i densly planted the top of the tank i get the best behavior out of them. not a great photo but you get the idea its indica rotala. water lettuce or preferably water hyacinth are the best floating plants for this because they get huge root systems.
pea puffers get along with allot of different species ive had them in community tanks for the past 15ish years the only fish they antagonized were my rams and young angelfish. but smaller quick schooling fish are nothing to worry about. however with any puffer occasional nipping should be expected.
