Because they come from running water, they require well-aerated water. This means they should have a filter or at least an air stone, and may well enjoy filtration that produces a strong current.

Crayfish are good at escaping, and tanks for them should have a tight-fitting lid that they cannot get out of.  They typically get to the top of the tank by climbing up any equipment that extends to the top of or out of the tank. Hiding places are important in order to make the crayfish feel secure, and there should be more hiding places than crayfish in a given tank in order to reduce fighting.  Crayfish like to burrow and will rearrange tank decorations if the decorations are light enough. They also eats live plants, so try not to get too attached to any decorating scheme or plant you put in their aquarium.

They are are best kept one to a tank, as they are likely to fight with each other. Some may also be kept in male-female pairs, which is necessary if you want to breed them.  There are also a couple of very small species in the genus Cambarellus that can be kept in groups if sufficient hiding places are given. Like Bettas, crayfish are sometimes used in animal behavior labs to demonstrate aggressive behavior – in both species the animals cannot actually get at each other.  The behaviors are observed as they threaten each other through the glass.

Crayfish are larger than most other invertebrates commonly kept in aquaria and large adults will need considerable space.  Ten gallons is enough for an adult of most of the North American species, but some of the Australian species can reach 16 inches and would need a 30 gallon or larger tank. There are a few dwarf species such as the Dwarf Cajun Crayfish, and Mexican Orange Dwarf Crayfish, that can be kept in a smaller fish tank or in a group in a 10 gallon tank if there are enough hiding places.

Crayfish will eat fish if the fish are small enough, so tank mates need to be considered very carefully.  Slow-moving species of fish are likely to get their fins damaged even if they do not get caught. The dwarf crayfish species can be kept with fish, but keeping them with very tiny fish or fry is probably not safe, and they should not be kept with large fish because the fish may eat them.

Crayfish can be fed on shrimp pellets or flakes, but there are often specialty crayfish foods available and many crayfish enjoy vegetables such as zucchini or peas.  If you live in a soft water area, you may wish to add calcium to their water, as this nutrient is important for growing a healthy exoskeleton.  Molting crayfish will eat their discarded exoskeleton to recover the nutrients, so this is often left in the tank.  Temperature requirements vary, but many species are happier in cooler water than the standard tropical tank.

Some Interesting Crayfish Species:

Procambarus alleni “electric blue”, Florida blue lobster
6-8 in, typical needs for a crayfish.

Procambarus sp. “Marble”
This species has no males.  The offspring are clones of the parent. More mundanely, it grows to about 4 inches in length and has typical requirements.

Cambarellus patzcuarensis Mexican orange dwarf crayfish
Thi species is tiny, at 1 to 1 1/2 inches in length.  If it can be kept was small fish, but not with large fish as the fish may eat this crayfish.  Many individuals can be kept in the 10 gallon tank so long as there are hiding places. It can stand warmer water, being comfortable in 60-82F.

Cambarellus schufeldtii Dwarf Cajun Crayfish
Very similar to the Mexican Orange Dwarf.

Cherax tenuimanus “Blue Marron”
This species grows large at 10 to 16 inches in length and requires a larger tank of 20 to 30 gallons.  It likes temperatures of 60 to 72 Fahrenheit, and care is otherwise as for most crayfish.

Sources:

Aquatic Community Aquarium Forum

canadiancrayfish.ca

McClure, Susan. Crayfish Care. Badman’s Tropical Fish.

They have their bad points too. They eat plants, poop a lot, and use space and oxygen you might have intended for your fish or shrimp. Snails can also act as an alternate host for some fish diseases, and for this reason you should never collect them from your local pond or lake.

The family Lymnaeidae is known as the pond snails. There are multiple species known as pond snails, and figuring out precisely which one you have in your aquarium may be more trouble than it’s worth. They are all hermaphroditic, and those seen in aquariums generally stay below 1 inch in length, although some seen in the wild can be nearly three inches.

Care and Feeding of Pond Snails:

They eat fishfood, algae, and soft leaved aquarium plants. They do not eat fish poop or have a noticeable effect on java ferns or java moss. Dissolved metals are often toxic to them, and fish medications based on metals, especially copper, should be avoided. Fish medications using dyes may also be toxic, although mine have survive Victoria Green B with no obvious ill effects. They prefer water that isn’t soft and acidic as they require calcium for shell formation. Mine is surviving in soft, acidic water, but its shell is showing signs of problems.

How to Avoid Pond Snail Overpopulation:

• Don’t overfeed. If they don’t have sufficient food, their population won’t explode.
• If you don’t want these snails, try picking over and quarantining plants before introducing them to the main tank.

How to Reduce Your Pond Snail Population:

• Put lettuce in a small container with the lid off. When snails collect in the container, remove it from the tank with the snails.
• Buy fish that like to eat snails. Puffer fishes, convict cichlids, certain african cichlids, clown loaches and yoyo loaches are sometimes recommended. But before you buy, check that the species you choose will fit in well with your other fish and not grow too large or require water conditions you can’t provide.
• Remove them by hand. If you have a lot, this will take a long time and you’ll never manage to get all of them.
• Use a snail killing chemical. However, chemicals that contain copper sulfate tend to be toxic to fish as well and need to be used with great care. You may prefer to use another method.

Sources:

How to Get Rid of Small Snails

Pond Snails, Bane or Boon?

Ryan Wood. Pond Snail. Planet Inverts.

The Living World of Molluscs. Pond Snails Lymnaeidae

Shrimp tolerate a wide variety of temperatures but temperature tolerances vary between species. Most will tolerate normal tropical aquarium temperatures, but some require higher temperatures and others are quite happy at temperatures lower than most tropical fish will stand.

Because shrimp keeping is a young part of the aquarium hobby, estimates of what temperatures a specific species like vary between sources. For example, the Amano shrimp is a common, well known shrimp in the hobby. Planet Inverts gives a temperature range for this species of 68-82F, while shrimpfanatics gives a range of 10-28C (50-82F) and most books on the aquarium hobby have no detailed information on aquarium shrimp at all! It is also noticeable that different captive-bred color varieties of the same species are sometimes given as having different temperature ranges. This is possible if the color varieties came from different areas or were kept under different captive conditions for long periods of time, but it is not very likely. It makes me suspicious of the information’s accuracy.

What can one do in such a situation? Pick what seems the most likely estimate for the shrimp you wish to keep. This is usually the parts of the range that overlap between sources. In the case of the Amano shrimp, that would be 68-82F. Watch your shrimp. Are they dying? Are they eating enthusiastically? Are they breeding? Adjust temperatures until your shrimp show the full range of healthy behaviors. Once you have this information, put your results up on the net and let other people know. In an area of the hobby this new, we all have the ability to add to what is known.

For those of you trying to pick a shrimp species, here are temperature ranges for shrimp with non-standard temperature tolerances. All information here is from Planet Inverts.

Aquarium shrimp that tolerate cool water (minimum less than 70F):

Amano Shrimp Caridina multidentata 68-82F
Bee Shrimp Caridina cantonensis “Bee” 64-78F
Caridina cantonensis “blue tiger” 69-81F
Caridina cantonensis “crystal red” 64-78F
Dark Green Shrimp Caridina sp. “Dark Green” 68-82F
Glass/Grass Shrimp Palaemonetes paludosus 64-85F
Golden Bee Shrimp Caridina cantonensis “Golden Bee” 64-78F
Neocaridina heteropoda 64-82F
Orange Bee Shrimp Caridina cantonensis “Orange Bee” 69-81F
Red Cherry Shrimp Neocaridina heteropoda “red” 64-82F
Red Tiger Shrimp Caridina cantonensis “Red Tiger” 59-81F
Snowball Shrimp Neocaridina cf. Zhanjiajiensis var. “white” 69-82F
Tiger Shrimp Caridina cantonensis 59-81F
Caridina cantonensis “white bee” 64-78F

Shrimp that require high temperatures (minimum 75F and up)

Brown Camo Shrimp Caridina sp. “Brown Camo” 78-85F
Cardinal Shrimp Caridina sp. “Cardinal” 78-85F
Harlequin Shrimp Caridina cf. spongicola “Harlequin” 78-85F
Orange Delight Shrimp Caridina sp. “Orange delight” 78-85F
Red Goldflake Shrimp Caridina sp. “Goldflake” 78-85F
Sulawesi Shrimp Sp. name not given, new intro. 80-82F

Sources:

Planet Inverts

Shrimpfanatics