Mud Crab Aquarium Care

[Linden]

Hello. I've written the following based on my own time scouring the internet and then personal experiences with my mud crab Gaston. 

 

 

Mud crab aquarium care. 

 

Tank setup:

Minumim 4ft aquarium. A 4x2 ft much better.  Like with turtles, larger footprint is important. Not so much how tall the tank is. Seriously big crabs. Be open to having a 6ft aquarium if you plan on risking tank mates (other than glass shrimp, snails and tiny fish). Unless your in Western Australia, you'll get Scylla serrata aka Green mud crab (not named green for being green. Can be brown and blue also). They can grow up to 30cms and 2.5kgs with 20cm claws. 

 Have a cycled aquarium with brackish water about 1.006-1.010 SG. Heated 19-25°c. PH around 7 or higher. Harder water is important. Crushed coral can help balance out soft tap water and the use of driftwood. Breaking up some cuttlefish bone in the water column is important. Calcium for shell development. They are from estuaries. So have a great tolerance for temperature and salinity fluctuations. 

 Decent filtration is a must as they are exceptionally messy eaters. I recommend a sump. The crabs are very strong and can snap heaters, damage power cables and move tubing. So a sump for the hygrometer and heater helps, with the benefit of the overflows and returns being secure. Also clamps to hold parts in place. Pvc tubing can be used to protect power cables and keep equipment protected. 

 The lid needs to be very secure. With only small gaps and also weighted down. The crabs are strong and can easily lift glass. Some additional glass pieces on the lid to keep it down is recommended. 

 

 The crabs will want to get their mouths above the water line periodically. So don't fully fill the aquarium. About 20cm deep. Deeper depending on if you have driftwood or rock climbing areas so it can still reach above water line. Note: ensure all rocks and driftwood are very securely and purposefully positioned. Remember they are very strong and can move unsecured rocks and driftwood. Poorly placed rocks could be moved and break the tank. Using larger rocks and wood is safer than easier to move small pieces. 

 Sand as a substrate is best. 6cm or so deep. Mixed with some crushed coral and aesthetic gravel. They sift through sand for scraps plus it will help fill cracks between rocks n such to secure them even more. 

 They will eat plants. So not a great aesthetic addition. 

 

 Don't put strong lighting on the tank. The crabs like to hide. Plus they'll grow algae over their carapace under too strong and or long exposure. Glass shrimp will help keep this down. 

 

Aquiring:

 Can be bought from a fish market. Sold as live food. About $50 per kilo. A standard mud crab will be about 0.8-1.4kgs. Google how to pic a healthy mudcrab. You want to select the healthiest male you can get (not the biggest). Note. They'll all be male. 

Transport in Styrofoam box or esky with a little ice. They'll wrap it in newspaper. 

 When home. Unpack it (keep the claw string on) then move it into a large container or tank with no water for about an hour as they 'defrost'. Remove the claw holding string as you move into their aquarium. Have a friend around to help with lid for safety reasons. 

 

Feeding:

 They are scavengers and eat a wide variety of foods. They will make a big mess when they do, so some glass shrimp, Malaysian trumpet snails and a few tiny fish are beneficial for cleaning up the shower of food particles. 

 My favourite foods to feed are small whole cooked tiger prawns and marinara mix from the deli. Some white fish cut into pieces then frozen. Repashy with added calcium (powdered egg shells or cuttlefish bones). Make big skeets in flat zip lock bags and freeze. Snap off a piece for feeding. 

 

 Can also feed worms, clams, scollops, crab pieces, garden snails, plant matter (like excess Elodea from another tank). 

A varied diet is important. But most of all is getting plenty of calcium in their diet. The repashy +calcium or a similar diy mix with agar agar, calcium, seafood and added vegetables is gold. 

 

 It might not take to eating well initially. I recommend using long planting tweezers. Carefully. Don't want them to grab the tweezers. 

 You can train them onto eating by attaching a piece of meat or prawn to some cotton string. Jerk it around infront of him until he goes for it. Might take a few tries. Don't leave large pieces of uneaten food in the tank to spoil. Be very careful putting hands into the tank. They can go from slow to very fast moving in an instant. 

Here's my Gaston. 

[Rare Aqua]

Nice write up, some really valuable information

[sdlTBfanUK]

I enjoyed reading this even though I don't keep crabs, it sounds like you need to be very commited but they are fascinating! Especially like the photo of one fierce looking beastie.

Simon 

[Linden]

Thanks. Yes. Before I got one. I spent months trying to figure out how to care for one well. But could only find agricultural breeding mass scale info from different countries and the odd Youtube video with no care info. 

Here now people can find more info in one place than I found online over months (specific to aquarium care for them). 

Highly recommended. A more advanced pet. 

[sdlTBfanUK]

Wow, you have done a fabulous job, that crab looks so healthy so you have definitely cracked it.

Simon 

[waffle]

AWESOME.

Re 'tiny fish' as suitable tank mates, this is so they are too small for it to catch, right?  I'm thinking maybe neon blue eyes since they are tiny and also prefer brackish water for breeding and the crazy mess the crab makes while eating might provide nice particulate food for the fry (http://rainbowfish.angfaqld.org.au/Cyano.htm, https://www.aquagreen.com.au/plant_data/Pseudomugil_cyanodorsalis.html).

Finally:

via Imgflip Meme Generator

[Mr Fisher]

Hay mate,

I love your post about your pet crab. I have a story for that leads into a few questions if you don't mind helping us out. I joined this site just to ask you a question.

So I fish a lot  and took my girlfriend away on a house boat on the Hawkesbery river and we went fishing for Jews and crabbing for muddies for dinner. We got crabs we ate and let go all our Jenny's and one massive one that had to be going on 3.5kg plus and a good 25cm or so shell size. MASSIVE.... Biggest I have seen in person and was in my parents pot on her first drop hahaha,, beginners luck as we thought we lost the pot cos it must have dropped right on a ledge or rock and the current dragged it into deeper water and the float went under. But on change of tide I noticed it 15cm under and we got it back with her massive Jenny in it. I only keep what I need and don't like keeping the Jenny's even though I have never caught one laden with berries that legally in NSW I have to let go anyway. But it is still strange watching $250+ swimming away as around $80 to $90 a kg live here in Sydney fish markets at the moment.

Our last crab we caught was destined to be brought home and kept alive today and eaten as Singapore crab for dinner tonight. He was the smallest boy we caught the hole trip and had been fighting as had a broken claw that's just healed so only a few weeks old. Anyways fishos nickname the girls Jenny's and no real name for boys. My partner asked my why I call girls this and not the boys a name??? So I told her.... I don't like naming my dinner hahahahaha and I guess that's it boys you eat and girls some like me never keep. Also boys have better meat/claws as you pointed out. So she said then we'll how about George. I told her yep some do call them that and also James,,,, she replies "George,,, yep George that's your name then". My partner is an animal lover, we have fish and she wants a pet snake but we have a cat. She had no issue with letting her massive Jenny go and said she felt bad about keeping the boys even though she like to eat them and knows how much we spend when we buy them.

So we get home yesterday with George in a tub of water and air pump. I know from past experience I can keep them alive like this for over a week and I just put the tub down and she was like soooooo what's going to happen with George? I told her we leave him there till ready to eat. She then got a little bit upset and felt that was meant. So I said we could always put him in a spare tank for now if you want and if you don't want to eat him you keep him as a pet.... Her eyes light up.. really..... Ok, is our tank big enough.

I was like,, ummmmmm, ummmmmmmmmm, wait....... did I just lose my dinner.... Damit,,,,,, One of those oh well moments hahahaha. So now we have a new Pet mud Crab call George and that's how it came about with no plan or knowledge of keeping a crab that got me googling and indeed found same as you. So thank you very much for your great post it's pointed us in the right direction. I am actually making my own tank to fit a stand going to be around 95 X 50 X 60cm and made from Plastic so not having to worry about breaking glass and our cat if he gets lose when we are out hahahaha. Also only cost me $150 and could make a tank 120x60x60cm if we had the space for it which is about bang on your dimensions. I'm going to try and set up like mangrovey environment and use plastic plants in the hope he does not eat and destroy them. Mixed size of river stone and a few coloured ones also for substrate. I will send you a few pics IV only just gotten back from Bunnings now, poor George is still in his box so will be a few hours yet. Also any extra advice is welcome

Our main thing was how much to feed him and how often??? He is probably around 2.5kg and a good sized boy. This trip was outstanding for the average size of crab we caught as said he was the smallest. Also how long do they live as I guess he is getting in in age as for his size. And can we just put eggshells in the water and he will eat it???

Again cheers for your great post and any advice you can offer us is great.

Cheers 

JJ

 

[jayc]

2 hours ago, Mr Fisher said:

And can we just put eggshells in the water and he will eat it???

Crabs don't eat egg shells. 

Are you adding egg shells for the calcium? Egg shells increase calcium in the water. It's not for the crab to eat.

Egg shells, coral and sea shells all release calcium very, very slowly. If you need a boost of calcium, you can use Calcium chloride, which will increase calcium as well as pH. Calcium chloride is the stuff that is used in Damp Rid for example.

[Mr Fisher]

Cheers for that info mate. Makes sense as we have shell decorations in our fresh water tanks and they need replacing every few months or so and I was surprised at the thought of them eating shell. We only have kept angles and a few others simple fish before. Not got any experience with salt, corals and calcium. Was not sure how it all worked so appreciate the explanation.

Cheers. Now just to know how much to feed him and how often.