The Puffer Forum

Hi guys,

I realized today I have some "plankton" in one of my brackish tanks. Must be the babies of on my unidentified fiddlers, although I had sworn the male is a different species.

They are far below 1 mm in size, but under the microscope I see they are actually alive. Had problems to catch them even with finest nets I usually use for Artemia.

Any advice on rearing them? Is there any chance for survival.

So far I put some of them in a marine tank with a powerhead, small skimmer, some corals (xenia and similar basic stuff). Should the skimmer be turned off for a while?

In Addition I have a running phytoplankton mini tank. I guess that's for feeding the first days.

Borrowed a camera for the eggs, but the larvae are too small for my hardware anyway.

Addition: I also separated some of them in brackish water from the parents tank and put them in a large glass without current and filter. Maybe I add a small powerhead or an aerator in this tank for oxygen, but no filter.

A thing I forgot: I suppose these things are fiddler crab babies because 1) the female had eggs for 2 weeks until today. the plankton occurred today. 2) It looks much like crustacean larvae I found in online sources and there are no other crustaceans in the parents tank.

What I'd need is:

- Salinity? I guess something between brackish and marine. More probably marine I fear.

- Food? I try phytoplankton first, anything else is too big. Paramecium are about to be bred, too.

- Temperature? I'll go for 25°C although the estuaries are generally a little warmer.

Any other suggestions are welcome.
BTW these things seem like good food for tiniest puffer fries.

Some pictures:

1: Mother with eggs (more than a thousand)



2: My setup (changed from brackish to marine, larvae are still alive and fed with phytoplankton)



Since I cannot take pictures of the larvae under the microscope a link to a site which has pictures. Mine look exactly like the first stage.

http://www.fiddlercrab.info/uca_lifecycle.html

Cool. From what I've read its pretty hard to raise fiddler fry and I beleive I read that they usually travel to the ocean.
Good luck!

kass wrote:Cool. From what I've read its pretty hard to raise fiddler fry and I beleive I read that they usually travel to the ocean.
Good luck!

Thanks. I "went to the ocean" last night. Subsequently added small amounts of saltwater until reaching marine salinity.

Day 2: I cannot see any larvae anymore in the parents brackish tank (bumblebee gobies are quite round, though) and the marine tank with corals (seems they liked them, too). But the ones in the big glass with (now) marine salinity and an aerator are doing fine:



Fed them again with phytoplankton I always have (just in case). I recognized they have developed some spots (maybe eyes). They now have the size of freshly hatched brine shrimp (the smaller ones).



I added some artemia eggs which should hatch in 24-48 and provide a further food source. Since the artemias also feed on phytoplankton they will be become quite nutritious until eaten.

Some more pictures takes before yesterday:

father


mother


eggs


Some comments are in the gallery.

wow cool pictures. How exciting, is it the first time this has occured?

She already once had eggs, but no larvae. Maybe I missed them the last time.

Still wondering if these small things become such "massive" crabs. His carapax is about 2" wide and hers is a little smaller (no comparison to other species, though).

I am on day 25 (hope I counted right) of the fiddler crab larvae experience. I learned so far:

bad

- they die in full marine, although water quality is good (0:0:2)
- they die in freshwater
- they do not eat Artemia AFAIK and rather starve
- they die in any newer tank although the tanks are cycled and neither ammonia nor nitrite occur. Using old substrate/filter does not work, the entire system must be long settled.
- the latter makes it unlikely I can raise a lot of them since all my older tanks are occupied. Maybe I try some internal refugium.

good

- they survive in brackish water (1.008-1.012)
- they are not filtered by a standard internal filter with foam
- they do AFAIK only feed on algae and other stuff in a long established tank

great stuff, some good info there for future breeding attempts

Brilliant. Keep us posted with any subsequent attemts. Crabs do, very occasionally, breed in aquaria. One of the most detailed successful reports is here:

http://www.aquahoito.info/sesarma/index.html

Admittedly a different family of crabs, but the generalities should be similar.

Cheers, Neale

great info there mate