spot some critters on the live rock that
don’t come out during the day, I caught
a glimpse of a crab hiding in a hole in
one of the rocks near the bottom of the
pile. It appeared to be about an inch
wide and was dark green to black in
color. Its legs were short and squatty. I
only saw it for a moment and didn’t have
time to photograph it. Any idea what
With a photo, identifying
hitchhiking crabs with any
level of certainty can be
very difficult, but without
type of crab it is, and will it harm my
corals or snails?
The nutritional value of the popular
phytoplankton products were recently tested
by 2 feeding trials on juvenile hard clams,
Mercenaria mercenaria. The results were
published in the November/December 2006
issue of the peer review journal Zoo Biology.
The products tested included; both
powdered and liquid products stored at room
temperature, the popular frozen concentrate,
DT’s® Live Marine Phytoplankton, A product
marketed as being a refrigerated live
phytoplankton but with more species than
DT’s, and a product by the same company
that is advertised as having the same
nutritional profile as live phytoplankton.
Which clownfish do you
think is the hardiest? I’ve tried
to keep ocellaris clownfish
mes but haven’t had any luck
keeping them alive.
Kingston, Rhode Island
a photo, I wouldn’t even hazard a guess
as to the identity of the crab you saw.
However, if I were you, I would try
to trap and remove this mystery crab,
as most true crabs will eventually
become problematic in reef systems,
opportunistically munching on desired
fauna, such as coral polyps and snails.
To catch the crab, you can try moving
the rock it hides in to a separate container,
waiting for the crab to emerge at night, and
then moving the rock—sans crab—back
to your reef system. But since, as you
mention, the rock you saw the crab in is
located toward the bottom of the pile, you
might have better luck using a baited trap.
Position a glass against the rock it hides in
and place some meaty bait in the bottom of
the glass. Sometime after lights out, the crab
should enter the glass to get the bait, but the
smooth sides of the glass will prevent it from
climbing back out.
Then all you have to do is remove the
glass, crab and all, the following morning.
You might catch a few desirable critters
in the process, but you’ll eventually get
“The commercial blend,
DT's® Live Marine Phytoplankton
seems to represent a good
substitute to lab grown algae
for clams held in ornamental
or experimental aquariums.”
Zoo Biol 25:513-525, 2006. © 2006
DT’s® Live Marine Phytoplankton was the
only product tested that was effective in
growing juvenile clams.
The results from all of the other products
tested were consistent with not feeding
the clams at all.
I must admit to being more
than a bit surprised that
you’ve had such a hard time
keeping ocellaris clownfish
n ocellaris alive as, in my humble
opinion, this species is fairly durable and
even well-suited for beginners. If you try this
species again, you can improve your odds of
success by choosing tank-raised specimens,
which are commonly available (albeit usually
more expensive than wild-caught specimens)
in the trade.
Getting to your question, the tomato
clownfish Amphiprion frenatus is among
the most durable of the clownfishes. It’s
also one of the bigger species, reaching a
respectable 5½ inches in length at maturity.
You should also be able to get captive-raised
specimens of A. frenatus, which are even
more “bulletproof.” D