I'd go with medium SA Pimelodidae or Heteropteridae that do not exceed 1' - Pimelodus pictus, blochii, tetramerus, maybe ornatus, Rhamdia quelen - that type of catfish. And I'd get a nice group, not one or two or even three.
Sorubim lima grow to 2'. Sorubim elongatus to 1'.
Sorubim lima grow to 2'. Sorubim elongatus to 1'.
