CRAYFISH(the bottom feeders)
Crayfish can be very interesting aquarium inhabitants, but it is often difficult to identify a species or even find information about its requirements in captivity. Before learning about some possible aquarium crayfish, we need to cover the basics of these intriguing invertebrates.
Crayfish are found in a variety of habitats. Occasionally, they are found in brackish water, and some species can survive in saltwater for several days, but no marine habitats are permanent locations for crayfish. They are solitary animals that reside in dens or crevices, which they defend against intruding species members.
This aggressive behavior can change under certain conditions, however. For example, some species, such asOrconectes virilis, are passive when they molt or just before. In some species, too, aggression depends on temperature. A rising or falling temperature may be a spawning trigger, depending on the species, and then the aggression is proportional or inversely proportional with the rise in water temperature. The pH is not generally an important factor with captive specimens.
Fish That Can Be Kept With Crayfish
With the small crayfish (such as Cambarellus), you can keep neon tetras, mollies, platies, swordtails and small catfish like Ancistrus.
With the bigger crayfish (like Cherax destructor), you can keep small fish as well as bigger fish like Aulonocaraand Pseudotropheus (Malawi and Tanganyika cichlid fish ), catfish like Ancistrus, Gibbiceps, South American cichlid fish, barbs, goldfish and labyrinth fish.
Normally the crayfish’s claws are too big and heavy to allow them to catch small, fast fish. One factor to keep in mind: When you buy a crayfish and put it in the tank, the fish will normally need about two or three days to get used to the fact that they are now sharing space with a creature that can catch them.
Crayfish are omnivorous. They eat plants and plant matter, detritus and wood, roots and, in many caves, bat guano. They are predators that hunt small invertebrates, such as snails, mussels, leeches and worms, and will eat their own kind on occasion. In the aquarium, they will eat all offered foods, including frozen red worms, snails, mussels, shrimp, krill and artemia; fresh carrots, corn and cucumbers (try nearly any vegetable); and all kinds of dried foods, such as flakes, wafers and tablets. They’ll sometimes eat fish and plants (frogs, too), but fish are seldom eaten because crayfish normally are not able to catch healthy animals. Injured, sick or recently killed fish and amphibians, however, are a welcome treat and eagerly eaten by crayfish.
Growth And Shell Replacement
Crayfish have a flexible exoskeleton (its “shell”) that is repeatedly shed as the animal grows. When an old shell becomes too tight, the crayfish prepares to shed it. The entire process of developing a new, hardened shell may take days or weeks to complete, but the actual shedding may be finished in minutes.
A crayfish will stop eating three days to a week before a shed. It will be more active during the day and much more aggressive toward other crayfish. Increasingly dark, transparent edges show on the stomach and edges of the carapace. Immediately prior to shedding (or possibly a few hours before), these areas may break open.
During shedding, the crayfish will lie slightly on its side. First, the eyes and antennae are freed, followed by the claws and legs. Finally, the animal frees itself of the remaining shell on its tail by exerting some strong movements. Exhausted from the process, the crayfish now seeks shelter and rests.
The new shell is still soft and pliable, and during this time the crayfish is at the mercy of its enemies. It is now easy prey. The danger of crayfish cannibalism is not as great as is often assumed. If another crayfish comes too close, the newly shed animal will assume a defensive position, standing tall with closed claws raised high toward the approaching intruder.
Occasionally, crayfish are unable to free themselves of the old shell and die. It is also possible that some limb sections will break off in the process because they are stuck in the old shell. Difficult sheds such as this can result in weakened animals that are more susceptible to predators and intruders.
After several days the new shell hardens, and the crayfish is able to resume its normal life. The shed exoskeleton — a source of calcium — is typically eaten by its owner or other crayfish.
Prior to the shed, the crayfish absorbs calcium carbonate from its exoskeleton and secretes it to form white half-spheres called gastroliths (also known as “crayfish rocks”) in its stomach. During shedding, the gastroliths are dissolved in the stomach fluid, releasing calcium to harden the next exoskeleton.
Crayfish can regrow lost limbs over several sheds, and a regrown limb has full function. If a crayfish loses a limb shortly after a shed, it will be replaced immediately with a smaller, weaker one. Young crayfish that shed more frequently are able to regain functional, normal-size limbs faster than older or adult animals. For these latter crayfish, the claws may never reach their former size again.
Crayfish will drown if they are kept in water that is significantly over their head for 3-6 hours without supplemental oxygenation. This makes air bubblers mandatory, and long bubble walls are the best.
Crayfish love darkness, so don't keep the tank light on a whole bunch, unless you are in the room looking at them, or unless you are meeting the tank's minimum lighting requirements for the plants, like 5-8 hours per day.
Crayfish are escape artists, because they are curious, and love to climb. Seal off all possible escape routes, especially the filter opening. If your cray escapes, it will dehydrate and die, in a few hours. There are very few good tankmates for crays, because crays eat tankmates Goldfish get BIG and POOP a LOT. I don't recommend them with crays. and tankmates eat crays. The tank must be cycled: ammonia=0, nitrites=0, nitrates 10-20 (40-80 means change the water now!), PH 7 or higher. Crayfish should not be in water with a PH of less than 7. Water parameters should be checked every 2-3 weeks, to make sure the conditions are good, healthy and stable. If you are uncomfortable with your water parameters for any reason, check them more often, so you will know when to take corrective action. Weekly water changes of 20-30% are recommended. Bottled spring water or tap water that has been dechlorinated should be used. When changing water, make sure the new water is about the same temperature as the existing water, to prevent temperature shock to the crayfish.
When your cray moults, leave the old shell in for one week, and then remove whatever (if anything) is left. The cray will eat the old shell to harden his new shell.
Do not feed your cray for a few days after he moults, because he will eat the old shell before any food you put in. So the food you put in will spoil.
When crays moult, they are very soft, weak, and vulnerable for about a week. So leave them in darkness, undisturbed as much as possible, during that time.
Crays should be fed shrimp pellets or crab and lobster bites as a staple, about the equivalent of ONE 3/4" pellet every day, at most. They also enjoy veggie treats from time to time (frozen peas, romaine lettuce, raw potato, carrot, cucumber, etc). And the occasional live minnow treat may be appreciated, too. Lettuce has to be weighted down with a rock. Use a rubber band to bind it to a rock. Do not over feed. The uneaten food will dirty the water; also over feeding your crayfish will cause them to be unhealthy, developing gelatinous shells.
Never put seashells in an aquarium with crayfish in it, because they cause unhealthy PH fluctuations.
Never feed live or uncooked shrimp to your cray. Shrimp can carry a disease that can be fatal to crays.
Never use copper-based medicine in a tank that has crays in it. The copper will kill the cray. Ally is correct for SOME crayfish. The ones she's talking about are the species that are considered to be "terrestrial" - these are the ones that dig holes in your yard and build a little "mound" around them. If you drop a pebble in the hole, you'll hear a splash because the holes go down to water (all crayfish have gills, which must be kept moist in order to breathe).
There are other species which are totally aquatic, however. Some are sold in pet stores (check into the electric blue), while others are natives. Billie gives good advice on their care, however, it should also be noted that when crayfish molt, they are vulnerable to larger fish and may become their meal! They should have an airstone or filter so they get oxygen to the bottom of the tank. And I'll vouch for them being escape artists - they can climb airline tubing and they can also travel a considerable distance outside the tank before dying.
Crayfish are freshwater crustaceans. They prefer foods like shrimp pellets or various vegetables but will also eat tropical fish food, algae wafers, and even small fish that come too close, such as goldfish or minnows. Their disposition towards eating almost anything will also cause them to consume most aquarium plants in a fishtank; however, crawfish are fairly shy and may attempt to hide under leaves or rocks. When keeping a crawfish as a pet, remember to give it a hiding space. At night, some fish become less energetic and settle to the bottom. The crawfish might see it as a chance for an easy meal, or a threat, and injure or kill it with its claws. If you have a crawfish living with other fish species, you will not need to scoop out as many dead fish, as crayfish are effective scavengers.I disagree with allyalex… i have kept a crayfish without air bubles or without be out of water for 2 weeks but now i have buble maker . Almost all water creatures need oxyginated water but dont need to be out, Water can be oxygenated without air. Some crayfish stay in water for there whole life.. Feed em worms, shrimp pellets, live fish for protein because crayfish need alot of protein. Include vegies and provide many hiding spaces. Provide a good filter and keep it at about 75 to 80 degrees F.Cray fish are almost like cleaner fish they'll eat leftover food from fish or they'll attack the fish. Not the best idea to put fish and crawfish together. Be advised that they tend to pollute the water pretty quickly and u will need to do lots of water changes.
they eat anything and everything ( they are referrend to as the garbage cans or bottom feeders)