Potentially Stupid Question..... :)

[Lil Tank]

I put a female fiddler crab in a 5 gallon tank with some tetras about a month or so ago. Everyone is getting along fine!

The crab molted yesterday and there is now an empty crab shell at the bottom of the tank.

Does anyone know if it is better to take the molted shell out or to leave it in or if it matters at all?

Thanks!

 

[nmonks]

Fiddler crabs need brackish water, and it's hard to imagine tetras living in brackish water, so something is amiss here…

In any event, leave the shell in place: the crab will eat some of it, and thereby recycle calcium. After a couple days, you can remove it.

Cheers, Neale

 

[Lil Tank]

OK cool. Thanks for the tip.

 

[pkppv]

OK cool. Thanks for the tip.

Yea, this is really up to you. You can leave it for calcium or remove it in an attempt to keep your water extra clean, but it doesnt doesnt quickly at all, so i would let the crab chew on it for a little while.

 

[mrp3]

I keep my tetras in brackish and they don't care theyve lived nicely for 6 months

 

[creeker]

I keep my tetras in brackish and they don't care theyve lived nicely for 6 months

mrp3, what species tetra and what is the specific gravity of your water?

 

[mrp3]

Cardinals and gravity?

 

[This Old Spouse]

I always left the shells in the tank and they'd be gone within a day or so.

I kept my fiddlers in with my female guppies. They all got along wonderfully.

 

[creeker]

Cardinals and gravity?

Specific Gravity of the water. For our purposes here, how saline is it? Those that keep brackish tanks generally use a hydrometer to measure this.

 

[mrp3]

I didn't know I had to measure it.

 

[Dieses Madchen]

Unless a fish is termed as a brackish fish, then it should only really be put in salt if you are treating a condition (but verify that the type of fish can tolerate salt.) Salinity of a brackish tank should be very low, like 1.002-1.006...it can be measured with a refractometer

 

[iliveinazoo]

Unless a fish is termed as a brackish fish, then it should only really be put in salt if you are treating a condition (but verify that the type of fish can tolerate salt.) Salinity of a brackish tank should be very low, like 1.002-1.006...it can be measured with a refractometer

Brackish water is anywhere between fresh and marine

 

[nmonks]

Close, but not quite. Brackish water certainly fills the gap between freshwater and saltwater, but you can add some salt to freshwater without creating brackish water conditions. Conversely, a marine aquarium can be run at a reduce salinity without being a brackish water system. Indeed, in the past this was often done with fish-only systems.

So, if you want to define brackish water from an aquarists perspective, the minimum specific gravity is about 1.002 at 25 C, which is about 15% the salinity of normal seawater. Anything lower than that and you'd probably find your brackish water not doing as well as you hoped. At the top end of the range, SG 1.018 at 25 C is low enough to keep marine fish safely, so that'd be the point at which you could call the salinity "near-marine". It's about 75% the salinity of normal seawater.

Everything between SG 1.002 and 1.018 is brackish water fishkeeping, with 1.002-1.004 being recommended for low-end systems where plants are a feature, and upwards of 1.010 for high-end systems where scats, monos and other big brackish water fish are going to be kept. Fiddler and red-claw crabs aren't fussy, but the ideal would be about half-strength seawater, i.e, around 1.008-1.012.

Cheers, Neale

Brackish water is anywhere between fresh and marine