Backyard Aquaponics
A place to discuss aquaponics

I bought two pet store yabbies to get an idea of the behaviour of the species, and given what I've observed I wanted to ask others whether what I'm seeing is normal behaviour.

My yabbies seem to be dead set on killing each other, they probably spend at least a third of their time fighting. One yabbie has managed to remove all but one of the legs on one side of the other one(which, as a side note, appears to have had no effect on it's ability to walk).

I'm feeding them carrot, if that makes any difference.

They are in a smallish tank with a 5cm koi, maybe slightly larger than an A4 sheet of paper on the base. There is a chunk of driftwood which they have dug a burrow under - one usually sits on the top of the wood whilst the other is in the burrow (when they aren't in a fight to the death).

I'm aware that yabbies predate their own species, but are they always so vigorous in that pursuit?

Yeah pretty standard I think cfuse.. My yabbies are fighting lots at the moment, they killed another one yesterday and this morning it's nothing but an empty shell..

EB, you sure the empty shell wasn't a moult?

Cfuse, i have seen both types of behaviours.............

the one you speak of where they set up a pecking order accordng to size and more recently a tank that have been very docile.

i cant give you a reason, but the tank with the docile ones had very poor water quality but an abundance of food.

opposite to the agressive ones.

i HAVE read that they fight less if they have plenty+more food, but it might be because.

try upping the feed, freeze a bit of veggies then put it in the water so it sinks.

small tank, very territorial.

Hi Cfuse,

I used to keep several tanks of these guys.

It's territorial fighting for sure.

1. You may have two of the same sex. It's warm so they may be trying to set up a breeding territory. (Depends how big they are.)

2. Feed them lots, it helps. They have smaller territories where food is abundant. I used to give mine fish food and vegies.

3. Hiding places. I recommend at least 50% more homes than yabbies. For two yabbies you need at least 3 places to hide. More is better. If all they have to hide under is the drift wood they will fight for ownership of it.

4. How big are yours? In clear water (such as your fish tank) once they get to about 6 or 7cm long, they need about a foot square each, minimum. Less than that and they need lots more hiding places. They can be more densely populated in muddy water (such as dams) 'cause they can't see each other as well.

5. Are they equal size? If not and there is a significant difference in size the smaller one is in grave danger.

In short, the biggest problem is going to be the size of the tank. In a tank not much bigger than a piece of paper, I'd say one yabbie would be enough. If you want to keep two in that area, they would need to be tiny.

You also probably want to know, they will catch and kill your Koi if given the opportunity.

any idea of the sex's? its breeding season. could be part of the mating process. lol.

as far as my experience goes, they are always aggressive to the point where you think they hate each other. Independent of sex or size, that in, until they decide to want a root, you can always tell when fertilisation has occurred. they get all chummy and hide in the same holes.
Also much tail raised and paddling of those little things under there mean there's interest.
In short, get hidey holes. They will kill each other.
Word to the wise: The shed their skin when they grow (he will grow back his lost legs) When they moult, they become reclusive and VERY defensively territorial, as their shell is so soft.
Their moults are usually transparent, until the yabbies age sufficiently, and then their moults look like perfect replicas... it's scary - and you can often think your yabbie is dead.
They eat lots of veggies, they love veggie pellets. Try carrot, cooked pumpkin, cucumber, etc. and have fun.

sex is difficult for me to determine until a successful mating. The the male is the one that didn't have eggs

But apparently you can tell by certain hooks under the tail that are used for holding on during sex...

I've split them up until I come up with something better.

The koi is bigger than them, I'm not really worried for it's safety(that, and the fact that the koi is deformed - it's tail curls upwards for some reason. It's the fish that I care the least about, which is probably why it's managed to outlive all of the other koi I had.).

You can easily tell the sex of a Yabbie. The males have 2 penes (lucky fellows) at the base of their bottom (4th set) of legs whilst the females have 2 sexual openings at the base of the second set of legs.

I did stress 'for me' I work much better with pictures than with words, as ppl like ROZ would attest to as they desperately try to understand my garble. :-)
So I have been told this (somehow in my head I had hooks near base of tail) but if anybody knows of a site with images (not drawings) pointing out these penes, I'd appreciate a link.

Also regarding the penes, snakes and sharks are also so endowed, however theirs is for convenience not concurrent use...

Here is one that might help? Where the screwdriver is pointing is smooth (female) if there were spikes on each side male.

Cheers mate :-) I think i know the protuberances you mean now... Thanks for the pic.

I really do worry about you KP...........

There was a picture posted several times displaying the difference between male and female...... probably in a "yabbie" thread....

Seek (search) and you will find......