Tropical Fish Hobbyist - October 2010

greater its buffering capacity—the higher the water’s alkalinity and the more stable its pH.

Coral-Banded
Shrimp
Won’t Clean

A month ago, I added a coral-banded shrimp to my 200-gallon reef tank, hoping it would demonstrate its cleaning behavior on my fish, but I have yet to see it do this. Is that unusual for this species?

John Pierrot via email

The coral-banded shrimp Stenopus hispidus is a facultative cleaner organism, which means it doesn’t depend on cleaning fishes to sustain itself. From my experience with this species, it isn’t all that likely to exhibit cleaning behavior in aquariums, though some specimens will. Certain shrimps of the genus Lysmata are much more reliable in this regard. For example, you can usually count on L. amboinensis, the scarlet or skunk cleaner shrimp, to exhibit cleaning behavior in captivity—both toward fishes and toward the hand that feeds it. The specimen currently residing in my 125-gallon FOWLR tank will immediately clamber onto any hand placed in the tank and give it the once over in search of something edible. L. debelius, the so-called blood or fire shrimp, is also a better bet than Stenopus hispidus when it comes to exhibiting cleaning behavior but, in my opinion, is not as reliable as Lysmata amboinensis in that regard.

Seeing
(Little) Stars

I have a 55-gallon FOWLR tank, and I’m beginning to see lots of little starfish on my live rock at night. They’re grayish white in color and are no more than half an inch in diameter. Also, they’re asymmetrical, with arms of unequal length. A friend and fellow hobbyist told me that they’re a type of pest starfish, and I should try to get rid of them before they spread out of control. Can you provide any information on these little starfish and tell me what I should do about them?

Casey Franks Springfield, Illinois

Q
A
Q

In my humble opinion, what you should do about them is enjoy them. From your description, it sounds like the starfish in your tank are a species of Asterina, which very commonly arrive in aquariums aboard live rock. They get something of a bad rap in the hobby because some reefkeepers report that Asterina starfish will consume SPS (small-

A

polyped stony) corals and other desirable polyps. Other reef hobbyists, however, report no such problems with them.

It may be that some Asterina species are more predatory than others, or that these starfish are more likely to exhibit predatory behavior under certain circumstances—such as in very sterile reef systems, which offer minimal grazing opportunities. In either