Tank Size

The following are basics for setting up a tank to maintain large numbers of Marbled Crayfish. Large colonies are great to use for “feeders” for carnivorous pets, as well as for fishing bait. (We recommend using frozen dead crays for fishing bait!).

First off – no, you cannot raise Marbled Crayfish in the same tank with cichlids, turtles and other animals which eat them. You will need a separate tank to raise the crays in when you want a supply for feeders.

TANK SIZE – The most common question we get from novices is “How Big of a Aquarium Do I Need”?  While a 10 gallon is fine for a couple of months, that 10 gallon is going to get smaller and smaller as these animals reproduce. And, like famous experiments with other animals, the more animals that you pack into a space is going to change a happy tank into a very competitive, even warlike environment. A good rule of thumb is – the bigger the colony, the bigger the tank. Start with at least a 40 gallon and go bigger if you can afford it. In all my cray tanks, I keep the water levels 2 inches or more short of being full, because crays like to find ways to get out of a tank. With a couple of inches of space between the water top and the top of the tank, you prevent the escape of adventurous crays. Also – crays like to play “king of the hill”. Since they will devour ALL live plants, I like to add some natural-looking fake plants, just so they can climb them and jockey for position. It seems to prevent social problems caused by overcrowding. And no matter what size tank you have, it will get crowded sooner or later.

CRAY APARTMENTS – To increase the number of crays that you keep in one tank, they need “private space” to dwell & multiply. On top of the sandy substrate, fill a large tank with “stacked” PVC pipe of 1-1/4 inches in diameter. Cut the PVC pipe into uniform 5 inch pieces. Put in enough PVC pieces that they cover a portion of the tank bottom and are “stacked” one on top of another, resembling a beehive when viewed through the front glass. It is interesting is that, given the 5 inch PVC apartments, each cray will immediately find his chosen tube. One cray occupies one tube (in most cases)! So it truly looks like a beehive, with one cray per “tube apartment”. Since the crays can crawl out of a tank, leave several inches between the top of the water and the highest level of PVC pieces. These act as “Cray Apartments” and prevent territorial scuffles. However, do not cover the whole bottom of the tank, or you will constrict the undergravel filter from working.

The statements provided in this website reflect the personal experience of the owner, not the results of academic research per se.