Protein sources, while not as necessary for culture stability as leaf litter or calcium, is the best source to encourage a large, thriving colony. With protein available, isopods reach breeding size more quickly than they would otherwise, and produce larger, healthier broods. This encourages both a stable population, and a rapid rate of growth. Porcellio and dwarf species are especially fond of protein. Protein sources, unless consumed quickly, will mold within isopod setups. We recommend offering protein on a weekly or biweekly basis and not offering more than what the isopods will consume between feedings.
The cheapest, most popular source of protein used by keepers is fish flakes. Initially, it was believed that flakes with a copper content should be avoided, but that has been proved untrue in the long term. Any flakes will do, we’ve have a lot of success with the brand TetraFin. Fish flakes can be purchased at any pet store and are available online. When offering fish flakes, place on the dry side of the setup to reduce molding.
Fish pellets are another widely available option for protein. Pellets may attract grain mites due to being partially grain based, and mold even more quickly than fish flakes due to this. Pellets also tend to be more expensive, and the isopods don't like them as much as other offerings anyway. Practically any food produced for fish is great to offer isopods – many keepers give their isopods dried shrimp, krill, bloodworms and other bait. Isopods really appreciate the variety, and it can be very entertaining watching an isopod attempt to drag an oversized shrimp into a tiny burrow. Shrimp meal, used for plants as a fertilizer, is both high in protein and rich in calcium. It's very cost effective since it is a byproduct of the shrimp industry and marketed to be mixed into gardens.
There are also commercial diets available on the market for isopods. “Morning Wood” is a diet produced by Repashy; this is produced specifically for detrivores like isopods. Other mixes like the Grub Pie or Complete Gecko Diets are full of protein great for isopods as well. Additionally, there are smaller companies that produce, bag, and offer their own mixes to the market. Many keepers practice offering leftover gecko diet from geckos such as crested geckos to their isopods – isopods will leave the dish clean as can be. These diets are rich in protein as geckos are opportunistic insectivores.
Dog and cat food are also protein-heavy sources that are an option for isopods. Even grain free options may attract mites, unfortunately, and has a tendency to mold. Again, quality does not matter; isopods don’t have high standards, but higher protein food will encourage better growth and reproduction.
Spoiled meat unfit for human consumption, such as chicken, beef, or pork is also an option to offer isopods. Offering meat should be done cautiously; not for the benefit of the isopods, but for their keepers. As meat decays and rots, it emits a terrible smell of death. Isopods happily eat spoiled meat and will swarm it, even with the awful smell. We routinely offer rats and mice that our snakes have rejected during feedings.
A simple, natural source of protein that shouldn’t be overlooked is the waste of animals – this is why isopods make such great cleaners! They will eat the shed skin of reptiles and their poop. The thicker scales of larger reptiles such as snakes may take some time to break down, but isopods to break down and eat it eventually. Dead invertebrates and their waste are great, too – many keepers have great success offering the frass from roaches, millipedes, and dead crickets and mealworms. Some keepers even go as far to offer heel scrapings and nail cuttings and yes, the isopods do eat and break them down eventually. Isopods will even eat and break down pet hair.
Protein sources are an important aspect of isopod keeping to master. The addition of protein to an isopod culture is greatly beneficial. Although protein may mold, the benefits far outweigh any negatives.