Crayfish are freshwater crustaceans with similar features to lobsters. Their small size and unusual form has them growing in popularity in the fish keeping community.
They have similar needs to fish, so looking after them requires similar skills. This makes them ideal for someone looking to expand into different areas of fish keeping.
One great trait is their omnivorous diet. You will quickly learn that as far as food goes, crayfish are not fussy. They eat the same foods as fish, and more. From fish foods to vegetables, crayfish will greedily eat almost anything.
As they grow from larvae to adulthood, the food they eat will change.
This article will walk you through the wide range of foods available to crayfish at all ages, both in the wild and in the aquarium.
Overview of Crayfish
Crayfish are freshwater crustaceans belonging to the order of Decapods. This order also includes lobsters, which are closely related, and often get misidentified as crayfish (and vice versa).
Crayfish and yabbies are the most common names for these creatures, but they are also known as crawfish, crawdads, freshwater lobsters, mountain lobsters, and mudbugs.
The name “crayfish” is shared with other animals in different parts of the world. For example, in Australia, New Zealand, and South Africa, “crayfish” is the name for a spiny lobster that lives in saltwater habitats.
It’s important not to confuse those creatures with the one we’re looking at in this article, the freshwater Astacoidea, Cambaridae and Parastacidae families.
There are over 600 species of freshwater crayfish spread across three families, two in the Northern Hemisphere and one in the Southern Hemisphere.
The largest range of crayfish can be found in North America, Australia, and New Zealand. They are also present throughout Asia and Europe.
Even the island of Madagascar is home to seven endemic species of crayfish.
Crayfish have been very successful in adapting and spreading across lots of different areas. In many areas some species have become invasive, such as the rusty Crayfish.
The average crayfish should reach a size of 6.9 inches and, just like all decapods, will have an anatomy which is made up of 20 body segments.
The segments are split into the cephalothorax and the abdomen. The cephalothorax is where the head and upper body segments fuse together, making it distinct from the abdomen.
Most segments have a pair of appendages attached. The segments without appendages change between species, so it becomes a way of identifying the crayfish.
Over time, crayfish are becoming an increasingly popular pet in the home. Their hardy nature and unfussy diet makes them easy to care for.
What do Crayfish eat in the wild?
Crayfish live in streams and rivers, so their natural environment will consist of mud, rocks, and vegetation, and a fast-flowing current.
The current is particularly important. If the water stays still then it is much easier for pollutants to build up in the water.
If they are in polluted water for too long, this can be fatal for crayfish. The current keeps the water moving, which flushes away pollutants and keeps the water clean.
Crayfish have a hard exoskeleton which makes it tricky for them to be eaten, but there are still plenty of animals that will try, Crayfish serve as a vital link in the food chain.
Potential predators include turtles, otters, wading birds, big fish and even racoons. There are lots of creatures above crayfish in the food chain, but there are so many more below.
Crayfish are omnivores so in the wild they eat whatever they can get their claws on.
In the wild, their main diet is decomposing animal matter or decaying vegetation, as these are the easiest food sources to get hold of and they can easily be ripped apart by their claws.
They also eat live small fish, if they swim by close enough. In the wild it’s difficult for them to catch live fish because there is usually somewhere for the fish to escape to, so it is much easier for crayfish to catch live fish in an aquarium because the fish are trapped in the tank and unable to escape (again, more on this later.)
It’s hard to think of another animal that eats so many different food sources; they will quite literally eat anything, from rotting leaves and twigs, to animal flesh, both rotting and alive, they’ll eat other crayfish and plants.
Crayfish are opportunistic feeders, which means that they will search around and eat whatever they can find. They are not particularly strong swimmers, so usually the food must sink to the bottom of the river before they can eat it.
They mostly use their claws and first two pair of walking legs (which have small pincers on the end) to pick food up, and eat it.
It is not easy to watch crayfish search for food since they are nocturnal. They wait until nighttime before leaving their shelter and scavenging food.
Because crayfish are not fussy eaters, they are very easy to cater for in the aquarium.
What do Crayfish eat in the aquarium?
Before adding crayfish to an aquarium, the tank needs to be as similar as possible to their natural habitat. Crayfish are not particularly demanding creatures, but a strange environment can lead to a hunger strike if they are too stressed to eat.
Studies have shown that crayfish can experience anxiety similarly to humans, which is why it’s important to create the right environment for them.
It should not be difficult to replicate these conditions. The bottom of the tank should have plenty of rocks and a thin layer of fine grain substrate (sand) for them to partially burrow into.
The rocks need to have cracks and crevices between them for the crayfish to hide in. In rivers these spaces would be used to hide from predators, as well as giving them shelter when they’re not scavenging for food.
Recreating a river’s currents can usually be done with the filter. Positioning the filter outlet at the surface should cause a small current through the tank, or you can use an air pump or water pump.
As we talked about earlier, crayfish often eat plants, so are likely going to cause damage to any plants that you keep in the tank. Even though they are likely to get damaged, plants are a good way to vary a crayfish’s diet.
Hardy, fast-growing plants are the most likely to survive abuse from feeding crayfish. Examples of these include hornwort and java moss.
Vegetation (such as vegetables, plants, and algae) may be used as the main source of food. It can be just as healthy as meat and is cheaper to buy.
Don’t cut out meat from the diet completely as the protein it contains is important for growth. When crayfish reach adulthood, proteins are needed in smaller amounts as they are no longer growing.
There are many food sources available for you to feed your crayfish. Varying the diet will give them plenty of nutrients and will also keep things interesting for them.
Pellet-type foods are ideal for crayfish as they quickly sink the bottom of the tank and are usually high in protein. Shrimp pellets are one of the most popular foods, but fish foods will be quickly eaten too.
Small live foods (shrimp and fish) are popular and make feeding times a little bit more interesting, since the crayfish will have to actively hunt their food.
If you have any leftover vegetables from your own food, you can drop them into the tank as well. This will give the crayfish something different to eat and also stops your own food from going to waste.
Leafy green vegetables are ideal as these are easier for the crayfish to break apart with their claws.
You might even want to make your own fish food, to make sure your Crayfish are getting the best mix of nutrients possible.
Crayfish help to keep your tank healthier and cleaner through their feeding habits. They will feed on bacterial or algal blooms, like other algae eaters, and keep the water clean.
Since crayfish may eat small live fish, they should only be kept with large fish, if any at all. The bigger the tank, the less the risk for the fish, since they have more space to escape.
When and how often do Crayfish eat?
Crayfish do not need to be fed in large amounts, especially when they’re adults. In terms of pellets, this could be a 0.75 inch pellet per crayfish per day when they’re young, and every other day for an adult.
Keep this quantity in mind if you choose to feed them other types of food too.
When you put food in the tank, it may not be eaten straight away, but you should see it disappear from the bottom of the tank when the crayfish become more active at night.
You do not need to worry if the crayfish are not eating their food, they should start eating again when they get hungry enough. If this becomes a persistent problem, try switching the type of food that you are giving them and make sure the tank and water is clean.
If you don’t feed the crayfish enough, they may start to fight and become cannibalistic. This could also happen if the tank is overstocked.
It is common for crayfish to sit in their hiding spots throughout the day, making it difficult to see them. If you want to see them more during the day time, try putting food around the tank to watch them scavenge, this will also encourage their natural behavior.
Some people choose to feed their crayfish using a pair of tongs, which helps them to get used to people and their artificial environment.
Try to keep the feeding routine regular. The crayfish will learn their feeding times and may venture out from their hiding spots when they think their food is coming.
Crayfish can be selfish animals. When you keep a few together in one tank they will grab a piece of food and run off with it. They might also try to intimidate the other crayfish to make sure they get food.
What do fry and juvenile Crayfish eat?
The life cycle of a crayfish starts with an oocyte (egg).
Once they’ve hatched from eggs, larvae will quickly grow to resemble a small crayfish. This takes 15 days, by which point they are only 0.5 inches in length.
This small size restricts their diet because they can’t fit the same foods into their mouths that adults can. At this age in the wild, the larvae would stay under the mother’s tail and feed on small pieces of floating food.
To recreate this in your aquarium you simply need to break down the food you give them to a suitable size. Check that the food is disappearing from the tank, and if you can, watch them eat to make sure it is definitely them doing the eating.
You can feed them crushed baby shrimp food which is available online and in some fish stores. This usually comes in a powder form which you can sprinkle into the tank.
Difficulty finding food is one of the biggest problems facing crayfish larvae, so providing sufficient food is key to decreasing mortality.
After the larval stages, young crayfish are just like miniature versions of adult crayfish. They will be going through growth stages and becoming larger, but their body will not change dramatically.
They go through the molting process, where they shed their exoskeleton up to a few times per years until they’re fully grown, the frequency of this can be affected by many different factors.
You can feed young crayfish the same foods as adult crayfish. Just make sure you feed them every day until adulthood because they need more energy for growth.
If you do have babies in the tank, it’s really important to make sure they are all being fed well enough, including the mother, because they will eat one another if they are hungry.
It should be clear to see that when keeping crayfish, their diet will be the least of your worries; they are scavengers and eat pretty much anything!
Their omnivorous nature makes them easy to cater for. They will happily eat live foods, frozen foods, fish foods, and vegetables, just to mention a few from an almost never-ending list.
This broad diet helps to keep the crayfish healthy, and if you vary their diet enough, they’ll be provided with all the nutrients they need.
If you care for Crayfish properly, these creatures are very rewarding to watch, and are a great alternative to freshwater fish, if you’re looking for something different and unusual to care for. Feeding crayfish is simple and should not stand in your way when deciding whether to keep some.
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