Live Rock In Brackish?

[crackmonkey]

Can live rock survive in brackish conditions of around 1.010, or any kind of coral?

 

[nmonks]

Hello --

Probably not. While some of the small invertebrates on living rock (particular things like bristleworms and crabs) may indeed be tolerant of brackish water, most of them won't be. I'm not sure where they collect living rock, but I assume from the sea rather than estuaries.

There are thousands of brackish water invertebrates, but few get routinely imported. Most of the ones worth trying are arthropods (e.g., Amano shrimps, amphibious crabs, horseshoe 'crabs') and molluscs (e.g., Nerite snails, Malayan livebearing snails). So while it is certainly possible to create a brackish water tank with invertebrates, it isn't as easy as with a reef tank.

On the other hand, it's certainly easier that doing the same thing in freshwater.

Cheers,

Neale

Can live rock survive in brackish conditions of around 1.010, or any kind of coral?

 

[andywg]

I have occasionally wondered on this. Nmonks is right in that any coral will not survive and any creatures brought in will also die.

My wonder is as to the importance of the life on the live rock for its filtration efficiency. One of the reasons it is so good in marine is because it completes the nitrogen cycle (converting nitrate to nitrogen gas). This is due in a alarge part to the somewhat anaerobic ares in the porous rock.

If anyone has a spare few hundred quid to throw at killing some LR... then it could make an interesting experiment. If it kept the nitrates down it would help reduce the frequency of water changes (which will save money on salt).

As I said though, I am not aware of any studies, amateur or professional, on the filtration efficiency of live rock in lower SG. As was mentioned to me, it may be that the movement of the resident critters aids the filtration in a reef and the rock will become expensive decor in a lower SG.

HTH

Andy

 

[nmonks]

There is a mangrove jellyfish (Cassiopea andromeda) that will do well in strongly brackish water, and some species of Aiptasia and Actinia (anemones) can be acclimated to brackish water, too. So there is scope for a brackish invert tank, it would just take some doing. Mangrove jellies in particular are photosynthetic, and not especially hardy in tanks (though they can be a pest in the wild).

I've kept shore crabs (Carcinus maenas) in warm brackish water and they do astonishingly well. They are very destructive and predatory though, so choose tankmates with care. Mine seemed fine with gar and Colombian shark catfish. Of course both these species view small crabs as food...

There's a tonne of Nerites species out right now. They're marketed as "onion snails" and "batman snails" and such like. They're all algae eaters and short lived in freshwater tanks. But in brackish, they should be quite easy to keep. Cardinia spp. shrimps are brackish, too, although they live fine in freshwater (as "Amano shrimps").

I think the trick would be to choose the right species, make sure you identify them properly, and then acclimate them slowly. But given how messy things like scats are, you probably want to choose only the smaller brackish water fish, if any at all. A fun project though.

Cheers,

Neale