black patch under sand

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kellane1

Aquarium Advice Regular
Joined
Dec 27, 2003
Messages
57
Location
australia
having just read the advice of the question posed regarding, "black spots on sand"it occured to me that i could have a potential problem and probably need to ask a question and rectify any potential problems.
Approximately a month ago i introduced about 10 australian yabbies, these are a near transparent crustacean, that live in sand around some of our creeks, they are easily obtained with a yabbie pump and i thought they would make good sand filters and maybe eat some of the detrius that accumulates on the sand.
Anyway, i think that a couple of them may have died and i now have one very large circle shaped, black or maybe dark purple stain against my front glass under the sand, it is approx 3" x 4" round.
There is also another smaller circle about three inches from the first one.
I surmised that it was just the bacteria feeding off the dead creatures and that it would go away in due course. This has not happened and my questions are as follows, can it be harmfull, should i dig it all out and remove it and what is it???
thank you all for spending the time to read this and any suggestions you may have..
kell
 
Is this the critter you are refering to... >>Blue Crayfish<<. If so, it does not belong in a SW environment.

It's always best to remove dead or decaying items from the tank when possible. As to wether you may have pockets of black sulphides would depend on the depth. The sulphides are a byproduct of strictly anaerobic bacteria which means it would need to be fairly low in the substrate to be a concern. If just below or near the surface of the substrate, it will not be sulphdes.

Cheers
Steve
 
creature

no the crustacean i am referring to is callianass upogebia, and is most definately found in salt water..
 
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