In my aquarium along with many different varieties of fish, I have 3 Red Claw Crabs, often referred to as Thai Crabs. The reason I got them was because they are very different, they look cute and they work well in my aquarium. Keeping them is as easy as keeping any of the fish that I have, though they do sometimes fight and should fish venture too close to them, they do often chase them, but cause no harm or attack them.
To look at the Red Claw Crabs are to begin with fairly tiny, no bigger than the lid of a Coca Cola bottle when they start out in life and whilst they grow, they don't outgrow the tank and become too big to look after or fit in with their habitat, infact they grow no bigger than 4cm in length. When I bought them from my local Marine Centre, I was told to ensure they had somewhere to hide, because they like to be out of the way and have their own space, give them something to climb up, on and in and ensure there is somewhere for them to be able to sit out of the water, either using a piece of driftwood or another aquarium ornament that would allow them to do this. My crabs are particularly inquisitive and as soon as a new ornament appears in the aquarium it isn't long before the are clambering all over it, often fighting with one another to figure it out and see what it is, especially if there is somewhere to hide. You also need to take extra care when making any changes to your aquarium as these crabs move very quickly and if they can escape they will escape. Steve and I had were one night sat watching a DVD when I saw something shoot across the floor, thinking it was a spider I shone the torch on my Iphone to find it was actually one of my crabs, who had escaped sometime during that afternoon when I had left the lid open and had escaped being caught my one of my cats.
My aquarium is now an established aquarium and after two years and I am now in the know when it comes to needing to clean the tank, the filter, when to top the water up, when ornaments need to be changed and so on. The one thing that did confuse me for a while was feeding these Red Claw Crabs. So back at the Marine Centre, I simply asked what I was supposed to feed them because I noticed that whenever I put a Plecco wafer into the water, one of the crabs would run out from wherever it was that they were hiding, steal the wafer and run off with it, meaning the Plecco wasn't getting his food and that left me in a quandary as to whether or not to put another wafer into the water in the hope the Plecco would get to it, but not wanting to overfeed anyone or anything else in the tank because this could lead to further problems, some of which I have mentioned in other reviews.
So I was given Hikari Tropical Crab Cuisine Pellets which are sold in a 50g bag for around £3-£4 and these pellets are specifically made for crustaceans such as crabs, crawfish, lobsters and other aquatic scavengers. The packet itself tells you everything you need to know about the pellets, how to use them and what is in them, which I found really helpful. These pellets are enriched with calcium and other important nutrients which your crustaceans need in order to survive, grow and develop. They also help ensure that your crabs remain their natural colour which is important and it also helps strengthen and protect their shells, again this is of utmost importance, especially because they like to climb and when mine are out of the water and want to get back into it, they simply jump, often misjudging other obstacles in their path, so the last thing I would want is for their shells to be cracked.
The Pellets themselves are brown in colour and they smell fishy. The Pellets are also really tiny in size, so tiny that I have to pour a few onto the palm of my hand to be able to feed my crabs. The instructions state that you should feed your crustaceans 1-4 pellets twice a day based on their size and try not to over feed them but with hermit crabs you only feed them once a week and again I took advice as to whether or not I use the advice on the packet or whether I use my own instincts when it came to feeding the crab and was told to do both, if when it comes to feeding time the crabs don't touch the pellets, then try again the following day because it might be that they have eaten fish and Plecco food and are not hungry.
As soon as I put the pellets into the water, the fish immediately smell them and try to catch them before they reach the crab, so the best piece of advice I can give is to distract them with the Novotabs which you stick to the glass and then, as best you can, aim the Crab Pellets directly over where your crabs are stood so that they can get to them. I tend to feed my crabs first thing in the morning when they are most active and then when I come in from work.
As soon as the crabs notice the pellets they run to them and its quite amusing to watch them pick the pellets up in their claws and shove one in their mouth and then with one in each claw, they run off to their little hiding place and you don't see them again for a few hours, I assume after they have eaten and had a nap.
I have always used these Hikari Tropical Crab Cuisine Pellets for my crabs and whilst I do use bloodworms and cucumber to feed my fish, which the crabs also eat, they do love these pellets. They are also inexpensive to purchase and the packet will last for at least 6 months before you need to purchase another one.