Mini Algae Eating Crabs

Mini Crabs
Uca pugilator

We grow and keep our Mini Crabs underwater.  These little guys originated from a couple different vendors, but mainly from Matamoros, Mexico and some from the coast of South Florida.  This is important to know since there are so many species of crabs out there for sale.  Our crabs can live underwater indefinitely, but as with all little crustaceans, they may prefer to get out of the water from time to time.  Commercially we use little rock houses neatly arranged and spaced apart throughout underwater tanks and pools.  Call them “Crab Garages”, if you will.  We do the same thing for our lobsters here too.  They just kind of back up into their own little space and hang out at “the house” until they want to cruise around and forage.  Be sure to arrange your crab’s home so that it feels comfortable and won’t want to escape.  A crab that is trying to escape is a crab that is not happy with it’s environment, such as poor water quality, or too hot of water, etc.  Mini crabs love to hang on gnarly driftwood as well, and may make your driftwood it's favorite hangout.

Mini crabs are interesting tiny creatures that are found in brackish waters, either in mud or sand.  They don't usually grow more than 2” inches end to end.  The male has one claw that looks like its too big for his little body.  He will wave it to ward off enemies, or maybe even when you approach your tank, and yet do the same to attract female crabs as a potential mate.  Females have 2 little claws.  In the aquarium they are happiest in groups or pairs, as sometimes one female will kill extra crabs in her tank.  This is less likely to happen in very large tanks.  It is recommended to house them in at least a ten gallon tank.  They will not thrive as single pets.  We would recommend about 3 or 4 Mini Crabs per 10 gallons just in case you have some losses if you end up with 2 in a 10gallon tank, then great!

Mini crabs must have some aquarium salt in the water to survive so absolutely use it in your tank.  We would never build a tank or pool here without it, so you must know that adding aquarium salt to your tank is much better than NOT adding it, so please take our aquarium salt advice seriously, we would never steer you wrong.  More on salt dosages on the link on the left called “Top Aquarium Secrets”.  Read it, remember it, live it!

Mini Crabs are not affectionate pets so touching them and “playing’ with them is not really suggested.  They are very interesting and entertaining to watch but the real reason to have these animals is to have them onboard as a janitor to clean up waste in the gravel bed, eat micro-organisms, and of course to eat algae!

Females will stuff food into her mouth one tiny claw after the other, but the male cannot eat with his large claw and must feed himself solely with the little claw.  The crabs sift the sand through their systems and get nourishment from the microscopic particles and bacteria in it.  Periodically these crabs will shed their shells.  As they ease themselves out of their old shell that has grown too small, you can see a whole new set of eight legs and two claws curled up inside.  If they lose a leg or claw it will grow back inside the shell and be ready the next time they molt.  If the male loses his large claw, when he molts the big claw will be on the opposite side from where it was.  They must be careful for a few days until the new shell hardens.  Actinic bulbs in your tank will be helpful in the reproduction of healthy shells with all your crustaceans.

Do not remove old shells from the water as crabs will consume the old shell over several days and it will provide them with the calcium they need to develop a hard new shell.  If the old shell remains in the water for more than a week, it may be removed, but it is unlikely that this will be a problem.

Mini Crabs do best in tank temps between 64°F and 84°F.  Ensure the temp doesn't fall below the minimum though.  A general water hardness of 100-200ppm and a pH of 7.0 to 8.2 is also best.  Like any other aquarium pet, water quality is important.  Crabs cannot survive for long periods of time in soft or acidic water.  Due to their temperature requirements, these crabs can be kept with most tropical or cold water fish and can be an ideal animal for many cichlid tanks.  Mini Crabs shouldn't be kept with slow moving fish.  Sick or dying fish will quickly be devoured.  Offer them H20 Stable Wafers or Crab foods as a primary food source, but don't feed too often, remember, they are in your tank to clean up the algae among other natural foods already in your tank, let them do their job.

  Freshwater Mini Crabs make fascinating pets.  They are active, hardy and a delight to watch.  Have Fun!