I have used the small Kordon breathable bags in the past. They work well with none spiny rayed fish. The last time I tried to ship some 1"-2" Lepidiolamprologus juvies, although small, they have a sharp dorsal spine. I was told after 24 hours the shipping carton was very wet inside, and each bag had about 50% less water than 24 hours before. Luckily I had only put 1 cichlid per bag so there was enough water left to survive, maybe half cup.