Fish are a potential source of entertainment and food for martian colonists. Species such as tilapia and catfish are relatively low maintenance, and can be fed a wide range of foods, including biological waste. Fish kept in pools or aquariums in public areas can provide entertainment for colonists when other species of pets may not be practical. Fish are a good source of protein and other nutrients.
How efficiently do fish convert the feed to protein? How can waste be effectively recycled?