Theyll be fine my female blackbelt was 13 inches in a 150 with a saddled bichir , ornate bichir both over 20 inch a fire eel 22 inch and a tire track eel 22 inch with 9 other fish for 5 years , no deaths to fighting i could pet all my fish especially da eels they r attention hounds.But yeak i bought her at 2 inch all black with red tail crazy i know but by 4 inch she looked all blackbelt funny but yeah she was casual till 10 inch then was a cool queen alpha chick over my female dovi and red terror , but suprised she got to 13 ,,huge their not all length but height too,just was amazed ,,i love the alphas in the spawn ,biggest fry is not always male,her colors were odd as young other females dark grey not black males aare lightersilver to grey. But she was cool not aggressive but territorial a lil , i saw aggressive beasts so my definition of aggresive might b less than many , i always do large pvc pipes n my tanks so theres options for hiding, good luck, all yeah they eat meat n high protein foods but should keep them on veggie type foods for beauty n health,herbivore cichs have longer intestines ,it takes them longer to digest high protein foods plus my vieja were always darker becaus of this but grew large.