Cleaner Fishes and Invertebrates -- Picky Fishes!

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Well-known member
May 22, 2006
Many marine fishes act like cleaner fish. Besides the obvious fishes specialized to be cleaner fish, there are quite a number of other fish which will 'pick' at other fish. The fish being cleaned seems to 'ask for it' by striking a submissive pose (aiming its dorsal fin away from the cleaner fish) or spreakiing out its gill plates, or sometimes even seeking out the cleaner fish.

One type of fish very commonly performing such a service are young Angelfish and young Butterflyfish. Especially the young Butterflyfish are known for their cleaning service. Within the Butterflyfish category, the young Genus Heniochus fish are the top cleaners of all the 'non-cleaner specialists.'

It is exciting for both the hobbyist new to marine fishes as well as the experienced ones to see their fish interacting in such a fascinating way. One often worries about fish compatibility and to actually see one kind of fish letting another kind of fish pick at it is amazing.

Here are some observations and facts:
1. Cleaner fish will pick at the host fish even when there are no parasites or dead tissue available;
2. Cleaner fish will eat parasites and dead tissue, but can't live on them; and
3. Cleaner fish don't like cleaning tangs (Genus Acanthurus).

So what's going on here? What are the cleaner fish eating if not dead tissue and parasites (they not being available or the wrong kind (see below)). What other benefit does the cleaner fish get?

Think about the questions above before you squint to read the answer far below, in smaller font. :eek:

It is mis-informed hobbyists that think that cleaner fish and cleaner shrimp will actually eat parasites off their marine fish that are below the fish's skin. A cleaner fish does not penetrate the fish's skin to get at parasites. The parasites on captive marine fishes are not the parasites that these fish eat in the wild.

Parasites such as Marine Ich (Cryptocaryon irritans) bury themselves below the fish's skin level. The dissection and inspection of the intestines of cleaner fish and fish that are specialized cleaners show that they do not eat Marine Ich parasites. Also, these cleaner fishes do not and will not touch flukes that are encysted below the skin level.

Cleaner fish cannot cure Marine Ich and many fluke infestations. This doesn't mean the infected doesn't seek cleaning nor does it mean the cleaner fish will not clean, but it isn't eating or helping the fish with this parasite. The cleaner fish is eating something though (see answer to question way below).

It may be fascinating as mentioned above, but this is one experience the hobbyist should not seek. It has always been an issue about what hobbyists do to the reef environment by removing fishes, but this is one clear case where putting cleaner wrasses into the display tank harms the reef.

Cleaner wrasses, such as Labroides dimidatus and some that are obligate parasite eaters set up cleaning stations on the reef. Two, three or four wrasses work the station. The wild fish learn where these stations are and come to them often (sometimes daily) for cleaning. When man comes along and removes one or two of these cleaner fishes, the station wrasses are overwhelmed. They can't keep up to the host fishes visiting. They run themselves ragged and die. If the collector takes all the fish from the cleaning station, the collector has destroyed that station. Either way, there is an increase in parasites on the reef fishes, more become ill, and there is a domino effect to the health of the reef.

Resist buying all obligate cleaner wrasses. DON'T BUY obligate cleaner wrasses. :mad: Don't encourage the breakdown of the reef ecology. Let them stay in the sea and skip this home experience -- PLEASE!!

If you want to see this relationship in action, stick to cleaner shrimp. ;)

The cleaner fish are eating the mucous coating of the fish they clean. The mucous coating of healthy marine fishes has an abundance of protein and other nutrients. Why not tangs? Because the mucous coating of tangs is thin, giving the cleaner fish very little to eat. Thus, the cleaner fish avoids tangs when possible. The young fish are getting a 'free' nutritious meal out of the deal which helps them to grow big and strong. :D Who's doing whom the favor? THUS a cleaner fish can lead to harming the captive marine fish!
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