Purple fresh water Crabs

[northboy]

Hi All.

We did a trip out to Mt Mulligan on the Sunday of the Australia day long week end, I go out about 6 times a year to collect new Blood for breeding and to observe and take water samples.

For now these are Holthuisana agassizi, the family group has had a name change and as I have some specimens with Peter Davies the curator of crustaceans at QLD museum, I wont get into the nitty gritty of it all, I will leave it to the Boffins. The Crab

Water conditions change through out the year and as they are seasonal creeks the full Fresh water Crabs mostly occur in. Full fresh Crabs are determined by there egg size, like Fresh water Cray fish they have a large egg about 2 to 3.5mm in size and when the young leave mum they are ready to rock and fend for them selves.

Water test results

PH 7.2 to 8

GH 2.5 to 4

KH 3 to 4

Temp 18 to 30 and in winter when they are under ground there is frost in the area

PPM 80 to 130

vis is around the 1mt

There are a lot of Old Wives tails about them

1 They need to get out of water? No they are more that happy to stay under water year around, if they are trying to get out all the time test your water, it will be because of Ammonia, NO2

No3 or Phosphates

2 They eat meat ? No, they will eat it, but Meat is not good for them, because they are mostly Vegetarian,a bit of Fish or Prawn is OK once a week or twice. Frozen Mixed

Veg is good as well a fruit, the only ones I don't use are Potato, sweet Potato, Lettuce and Pumpkin

3 They eat fish? I have kept them with fish for years with no trouble, there will always be that exception that is a fish hunter but they are rare, if they are hunting it is because

They are not getting enough food

What you need to keep them.

Don't keep them with your favourite shrimp as Murphy will step in and it will eat your shrimp, how ever I keep them with Shrimp with out problems.

They need two shelters at least to every animal, this is so when they shed there shell to grow they can hide while they harden up, because when they come out of there shell they are like a lump of jelly, very soft and a target for tank mates, When they shed they split at the back and pop out realy fast.

Sexing is the same as all crabs.

Breeding is easy, I achieve it by diet manipulation, first you must keep them in there own tank in a trio of 1 male to 2 or more females in a minimum of a 60lt tank or bigger, the next must is to keep up the 1/3 once a week water change, more water changes are better, then diet, for about 2 months they get 100% Veg, then I change to 60%Veg and 40% Protein any is fine except red meat. When you see eggs under the tail of the female move her to a smaller tank using water from her tank so as not to stress her as she may drop the eggs, if you can move her in her cave all the better. When you have young scrunch up some onion bags for them to shelter in, so they don't eat each other, up to about 2cm shell size they are hard on each other. Past that they are OK with 2 shelters to each animal.

The drive out looking at North Cairns from the Kuranda look out

If handled gently they don't bight but if you grab them they are going to defend them selves. Agassizi are a crab of many colours, Red, Red stripes, Purple, Purple with bright yellow legs, White, Black, Hot pink and Sky Blue and no doubt many more.

There are also 7 species of true fresh water crabs from the Southern Atherton table lands to the top of Cape York and beyond, there are also many fresh water crabs that have planktonic young and are there fore not true fresh water species so to speak but will live there whole life in fresh water.

The creek from season to season

Another view

As for breeding there is huge potential for colour morphs because of the regional variation.

A piece of drift wood that has been there for years and still baffles us LOL.

More to add later Bob

Bob

[fishmosy]

Fantastic stuff Bob, first account that I have come across regarding the breeding of freshwater crabs. Have you received any interest in these from overseas as I know crab keeping has become popular in Europe over the last few years?

[Baccus]

They look a lot like some of the fresh water crabs I have seen being kept over seas, but sadly thier common name escapes me at the moment. They look great and I can see them becoming the next best tank friend, with people striving for special colour morphs.

Just had a quick look and from memory the ones being kept overseas might be called Vampire crabs and or Panther crabs.

Ps I like the butterfly shape on the back of one of them :redface-new:

[northboy]

We have SO many Crabs here both species and colour variations that you could not keep them all. I think they will take off as they get better known.

Breeding of the true freshies is not hard at all.

Bob

[pappyy3]

Beautiful Part of the world Bob ... so jealous ;)

[Gbang]

amazing there bobby!

[wayne6442]

hi bob, Will we be collecting some of these during my stay? wayne

[northboy]

WOW Gbang Bobby? I have not been called that for years LOL When I am realy in the crap its Robert! come to think of it I get Robert a lot?

Wayne, no it is a 2.5 hour run, not unless you want to can one of the other days and there is no shrimp collecting on the way to the Crab grounds

Robert ?

[northboy]

I should have added that the Orange tinged ones are Female and the Purple are Males.

Bob

[wayne6442]

Hi " Robert" I actually saw some of these crabs for sale at City Farmers pet store on the coast the other day, I think they wanted $15.00 each for them first time I have seen them up close.