I wouldn't do clown loaches with those dimensions. You CAN, but it's going to be cramped. Have you looked into some of the fish related to the clown loach? They are very beautiful, very similar in behavior, but stay much smaller so you can have a lot more too. Look up "botia kubotai", " botia histrionica", "botia almorhae" and "botia striata"
You could do some of the calmer central and south american cichlids with these fish. Severums, or certain geophagus species would work nicely. Angelfish are also an option.
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Loach count: 21
Baby fish count: 700+ (shelldwellers, gbr, angelfish)