Stocking density for dwarf crays?

YuccaPatrol · Post by **YuccaPatrol** » Wed Sep 20, 2006 4:18 am

I am converting a 29 gallon and a 10 gallon *fish* tank into breeding tanks for dwarf crays (Cambarellus diminutus) which I hope to bring home on Friday.

The profile for Cambarellus shufeldtii recommends keeping them with lots of hiding places and also says that they are generally peaceful with their offspring.

Approximately how many individuals would be appropriate in each of these tanks?

Because my interest is in breeding, I need to find a balance between having the largest population/gene pool and a stocking density that will keep them all happy and breeding.

Post by **Mustafa** » Wed Sep 20, 2006 7:38 am

You can put between 5-10 adults in a 10 gallon that has lots of cover. You can fill half of the tank bottom with java moss, which should provide enough cover for both the adults and possible offspring. Fill the other half with leaf litter, which will provide some food for adults (leaves and *maybe* some micro-organisms, and offspring (micro-organisms). That should work out pretty well. I would start out with only about 10 animals in the 29 gallon, too, just to give them more space for their offspring. Also, with less animals and more water your water parameters will be better and more stable over the long run.

YuccaPatrol · Post by **YuccaPatrol** » Wed Sep 20, 2006 8:22 am

Thanks a lot, Mustafa.

That helps me to know how many individuals I should collect (assuming that I can find them and they are in abundance). No need to remove any more from the wild than I can adequately house.

I'll set a goal to collect 30 specimens, with extras to be placed in my other shrimp tanks for safe keeping.

The Fisherman · Post by **The Fisherman** » Wed Sep 20, 2006 11:18 am

Interesting info, I will keep that in mind if I ever keep dwarf crayfish. (Which I want to at some point)

Thanks for posting

-John (AKA: The Puffer Ninja)

Post by **Mustafa** » Wed Sep 20, 2006 12:29 pm

Alternatively, you can forget about the java moss and just fill the whole bottom with leaves. I'm collecting more and more evidence that this setup actively reduces nitrates. It appears that the decomposition of the leaves utilizes nitrogen. Some journal articles I've read refer to it "on the side" (i.e. not their main topic) and I am still researching this issue, but my own nitrate measurements seem to confirm this hypothesis. The decomposition of the leaves in connection with the increased biofilm and algae activity (due to lack of nutrient and light competition by plants such as java moss and others) seems to work hand in hand to eliminated nitrogenous compounds. Preliminary data suggests that this might reduce phosphates, too, but I'll have to do more measurements to confirm this.

Just a thought.

The Fisherman · Post by **The Fisherman** » Wed Sep 20, 2006 1:19 pm

Interesting idea Mustafa. So you are suggesting to ONLY use leaves as the substrate? No sand, gravel etc.?

-John (AKA: The Puffer Ninja)

Post by **Mustafa** » Wed Sep 20, 2006 7:18 pm

It's up to you. It's ok to have a thin layer of gravel or sand. I have some thin substrate in the vast majority of my tanks.

badflash · Post by **badflash** » Wed Sep 20, 2006 7:21 pm

Mustafa, do you feed your shrimp & crays, or just let them go from what comes from the leaves?

Post by **Mustafa** » Wed Sep 20, 2006 7:35 pm

badflash wrote:Mustafa, do you feed your shrimp & crays, or just let them go from what comes from the leaves?

Good thing you mention that. I meant to clarify that earlier in this thread as it sounded like I just put leaves in there and that's it. No, I feed both my shrimp and my crays. I feed the crays more (just like my Macros) as their diet is different from dwarf shrimp. They don't really graze the biofilm and algae in the tank and need more additional food.

The food I give the shrimp both feeds them and the micro-organisms. That's why you can afford to feed shrimp less, as they are grazing on micro-organisms all day.

bjar · Post by **bjar** » Thu Sep 21, 2006 2:24 am

regarding the decomposition of the leaves utilizing nitrogen.It makes me think of some things I have read about gardening :that you should ad nitrogen rich material to a compost to make work well.I think I have also read that you can ad barley straw to your garden pond to get rid of alge
and that it works becouse the decompostition utilize some of the nitrigen in the water.

So I does make sense that it could work similarly in the aquarium with leaves.

YuccaPatrol · Post by **YuccaPatrol** » Thu Sep 21, 2006 4:12 am

I came across this nugget in a news release from Auburn University's agricultural experimental station that talked about using hay as a supplement in commercial crawfish ponds.

In the Auburn ponds, the higher stocking rates are fed a specially blended crustacean feed which has produced very good growth results. However, Rouse points out, when traps with the crustacean feed are placed in water in which the Redclaws have been fed hay, trap catches are reduced for several days. "This indicated to us that Redclaw eat hay and the hay might serve as a good supplement," Rouse commented.

With the assumption that hay would be an easily purchased source of leaf litter in a man-made pond that likely does not have trees surround it, this information may support some of our ideas about the value of leaf litter for both shrimp and crayfish.

bjar · Post by **bjar** » Thu Sep 21, 2006 5:33 am

Alder leafs is the main food for wild crayfish here in sweden ,not sure how
specialised most crayfish species are in general though when it comes to food.

Post by **Mustafa** » Thu Sep 21, 2006 7:17 am

YuccaPatrol wrote:With the assumption that hay would be an easily purchased source of leaf litter in a man-made pond that likely does not have trees surround it, this information may support some of our ideas about the value of leaf litter for both shrimp and crayfish.

It's true (and I have observed it) that larger crayfish species eat lots of plant material (both dead and alive) including leaves, but the Cambarellus species (which are all "dwarf" crayfish by the way) don't utilize that food source as much. I've only seen them nibble on leaves once in a blue moon and only once the leaf had become very soft after decomposing. In my tanks they prefer going after pellets and hair algae. The leaves provide cover for the adults and young, food (micro-organisms) for the young and additional food for the adults once the leaves have become very soft.

Mothi · Post by **Mothi** » Fri Sep 22, 2006 12:01 pm

What type of leaf litter are we talking about? I have seen almond leaves I think for aquariums, but not really much else.

Neonshrimp · Post by **Neonshrimp** » Fri Sep 22, 2006 12:36 pm

Mothi wrote:What type of leaf litter are we talking about? I have seen almond leaves I think for aquariums, but not really much else.

Here is a link to a much discussed thread on the different leaves one can use in tanks. If you search "Oak Leaves" you will find more

.

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