malawi cichlids in a 20g

Just do a google search on them and you will come up with all the information you need.
I would say you could do 5 in a 20 gallon long, two males + a couple females for each.

Two common shelldweller species are:
Neolamprologus multifasciatus
Lamprologus ocellatus


They like sand, a few rocks, high ph, hard water, and lots of snail shells to live in.
 
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