Keeping invertebrates can be enjoyable and rewarding, though not all hobbyists have ventured into the crustacean realm yet. If you've wanted to keep inverts and aren't sure where to start, or just need some information and recommendations,
Before we get started, keeping shrimp, snails, crabs, and crayfish is fairly easy and straightforward, but there are several things to keep in mind when adding these to your tank.
Calcium is necessary to help build and strengthen invert shells. One easy method to ensure your critters have access to calcium is to put cuttle bone pieces in your tank, but you can also purchase other supplements, such as calcium mineral rocks, or provide food that has calcium added to it already. If you use cuttle bone, you can start with chipping off a small piece and tossing it in the tank, where it will slowly dissolve and enter the water column where your pets will be able to absorb it.
When using any medication or chemical in your tank, be aware that copper is lethal to inverts, so you will want to either check the ingredients or separate your fish and inverts before using any copper-containing products.
Some invertebrates are more mild mannered than others; you'll want to be sure the fish and inverts you plan on housing together can coexist peacefully, both in water conditions and typical behavior.
All invertebrates will molt (shed their exoskeleton) from time to time. When this happens, they are vulnerable and will appreciate and utilize hiding places in the forms of rocks, caves, driftwood, decorations and plants. Also, some crustaceans will eat the old shell for the nutrients contained in it, so this is normal behavior and nothing to be concerned over if they do. If not, however, you will want to remove it.
Just as with any animal, we strongly encourage doing research on the pet(s) you plan on obtaining prior to acquiring them to be able to provide the correct and best care for them.
Invertebrates can be sensitive to rapid changes in water temperature or parameters, so they will want to be acclimated slowly to a new environment. You can read our blog here on ways to acclimate livestock.
Legs give inverts a higher ability to climb out of the tank, so it is recomended to use a fitted lid on your aquarium to prevent your pets from escaping, which can lead to their death.
Recommended inverts? Glad you asked.
Scientifically known as Caridinia davidii, these are popular in the hobby, partly due to their ease of care, partly due to the vast color varieties available, and partly due to their level of activity in the tank. Very peaceful, they can be kept with a number of fish (so long as the fish aren't large enough to consider the shrimp a meal). Read our blog here on Keeping and Breeding Cherry Shrimp.
Also becoming a more popular aquatic pet, the dwarf crayfish (also called CPO crayfish) remains small in stature and big in personality. They're also very hardy and adapt to a wide range of water parameters. If keeping more than one, you will want to ensure there is plenty of space for each to have their own area, and to provide many hiding places; this is especially useful when they molt and are more vulnerable to predators or harassment.
Dwarf crayfish are often kept with fish, and for the most part, are too small to cause harm to the fish. However, they may go after cherry shrimp, or may try to clip the fins of slow moving fish or those with long fins that flow in the water. Dwarf crayfish can be found in a few different varieties and color variations - orange, blue, olive, and reddish-brown are the colors most commonly available, and colors will have varying shades.
While not as colorful as cherry shrimp, these are also known as algae-eating shrimp, and for good reason. Slightly larger than cherry shrimp, they offer the benefit of helping with algae control. Like dwarf shrimp, this shrimp will do well in a temperature range of 60-80F. Along with algae, they will eat fish flakes, bloodworms, shrimp pellets, and algae wafers.
These are my favorite snails, mostly because they can't reproduce in freshwater, so there isn't a risk of a sudden snail infestation. Nerite snails will snack on algae happily; if there isn't enough algae in your aquarium, you can also offer algae wafers or blanched vegetables. Of course, some hobbyists have other snail types, such as mystery or trumpet snails, that they prefer for various reasons, and it all comes down to personal preference. But nerite snails have worked well for my aquariums, while others presented challenges the nerites did not. (Your mileage may vary; snails can be a great addition to your tank, though most types can reproduce quickly). If you have another type of snail, however, and see a large increase in the amount of snails in your tank, you can always add assassin snails to help control the population.
Since I am talking about my faves, this is my all-time favorite aquarium shrimp. These go by a few different names – flower shrimp, fan shrimp, Asian filter feeding shrimp, and Singapore wood shrimp are a few other common names. Bamboo shrimp don't typically make the list of recommendations on many sites, but they should. They are large, peaceful, and easy to care for. These shrimp extract food from the water, and will look for a column from which to feed. They particularly like sponge filters, where they will frequently feed from the inlet. The bamboo shrimp needs warmer temperatures and doesn't tolerate the wide range that other shrimp do; it should be kept around 75-81F. Using live plants is useful because they will offer floating, edible vegetation, and will sometimes provide a place for your shrimp to hide behind or underneath when getting ready to molt.
Vampire shrimp are a cousin of the bamboo shrimp, both in the atya genus; they are the same size, have the same care requirements, and are filter feeders as well. For both of these shrimp, the bigger the tank size, the better. A longer rather than taller tank is recommended so the current can travel quickly through the aquarium, and also so there is more floor space for them to explore.
While many crayfish are known for spending much of their time hiding under rocks, the electric blue crayfish is not only very active, but extremely hardy as well. Their bright blue coloration easily adds to their appeal as they explore their environment. It's recommended to house these in a minimum 30 gallon enclosure, as they can get larger than the other inverts on this list, usually reaching an adult size of 4-6 inches.
The crayfish will also eat any fish it can catch, so keep that in mind if placing with tankmates. One plus with these is they are known for cleaning waste in tanks. Of course, there are numerous types and colors of crayfish available, so you may want to research some other crayfish options. The care requirements are similar between crayfish, though there are variations in behavior, color, and patterns.
These are fully aquatic crabs with hair structures on their claws that are shaped like pom poms, hence their name. They will eat food that collects on these poms, but they are also omnivorous scavengers. These crabs are peaceful and make good community tank residents. If keeping a pom pom crab, be mindful they are active and good climbers, so they are known escape artists - a tight -fitting lid is a must.
This is another crab that's fully aquatic, but is smaller than the pom pom crab. The Thai micro crab typically reaches no more than .6"" in length, including its leg span. They, too, are filter feeders and will use hairs on their claws to filter particles from the water. A group of 3 or more is recommended. Because of their small size, care should be taken not to house these crabs with fish that may view them as a meal. They thrive in heavily planted tanks, as they like to hide among plants and driftwood. One benefit of these miniature crabs is that they will graze on algae. As omnivores, however, they will also need sinking food and will also appreciate meaty treats.
Vampire crabs are semi-aquatic, so they would actually need a paludarium rather than a full aquarium; however, they're worth a spot on Josh's Frogs Top 10 Invert list. While they're known to spend more time on land than in water, they will utilize the water at times and will need part land, part water for their setup. A plethora of color variations exist with this species.
Plants - both terrestrial and aquatic - are appreciated by the vampire crabs; they don't usually bother live plants, but may eat dead or rotting plant matter and will often help to ""clean"" plants as well. As adults, they don't generally get larger than about an inch. An omnivorous diet is recommended - along with insects, worms, and veggies, any type of aquatic food is a welcome addition. These are opportunistic scavengers and will sometimes hunt, so other tankmates (outside of the particular species of vampire crab being housed) could be at risk of becoming food. Some keepers have housed vampire crabs with larger shrimp or snails successfully, though they may still end up being eaten.
Like other inverts, vampire crabs need plenty of hiding places in the forms of plants, caves, rocks, etc.
The lack of these hiding places causes much stress on inverts, and could eventually lead to illness or death.
Overall, invertebrates are not difficult to keep and can make fascinating aquatic pets for a variety of tank setups and sizes.
TFH Magazine article - Fantastic Freshwater Inverts