Grouper at cleaning station - Melinda Riger @ GB Scuba


Today is going to be about Jaws – not those sinister-music-sharky types, but a look at the dentition, gill arrangements and oral hygiene of groupers(s). First, though, the vexed question of the correct plural for a group of these fish. I tackled the complex 3-option correct plural of OCTOPUS a while back. Now another problem piscine plural has cropped up.

Tiger Grouper - Melinda Riger @ G B ScubaThe short answer is that the plural is usually ‘groupers’, but also – perhaps less commonly – ‘grouper’ (there’s a similar situation with plural of ‘hare’). One online source suggests ‘grouperer’, but that just seems cumbersome. I think there may be a useful distinction to be made here. When talking about grouper of the same species, one could say “I saw 17 Nassau grouper today”. But where reference is made to mixed species, “I saw plenty of groupers today” implies that there was more than one species – black and tiger, maybe. 

Grouper at cleaning station - Melinda Riger @ GB Scuba

Grouper - Melinda Riger @ G B Scuba

In some of these photos you’ll notice tiny fish attending to the grouper. These are CLEANERS and they are an essential part of the bodily and oral hygiene routine for larger fish species. The big fish call in at so-called CLEANING STATIONS, where the tiddlers remove parasites and dead skin, and polish up the gills. They will even enter the fish’s mouth to pick bits from between its teeth – the deal being that they will not be eaten. This mutually beneficial arrangement is called ‘cleaning symbiosis’ and is carried out by (for example) gobies, wrasses and cleaner shrimps.

Peterson’s cleaner shrimps and cleaner wrasseGrouper with Peterson's cleaner shrimps and wrasse - Melinda Riger @ GB Scuba

Some of these photos show groupers with open gills as well as open mouths, an invitation to the cleaners to do their work. I’d intended to write about how and why gills work but I’ve thought better of it. There’s a lot of detail about chemical exchange involved that, when I looked more closely, seemed rather dull… and therefore outside the remit of this blog, which includes trying to avoid ‘dull’. If you really want to know more, Wiki has a good article HERE. Good luck with that….

Grouper - Melinda Riger @ GB Scuba

Credits: All photos Melinda Riger, Grand Bahama Scuba


Black Grouper - Arnold - Cleaning Station - Neon Gobies ©Melinda Riger @ G B Scuba copy


A while ago now, I wrote a detailed post about so-called fish ‘cleaning stations’ – the special spots on the reef where large fish can go to have small fish buff up their scales and floss their teeth. You can read all about it HERE.

I have accumulated a number of new photos from expert scuba diver and underwater photographer Melinda Riger that demonstrate this phenomenon. A big fish with a normally voracious appetite will patiently wait while gobies and other small fry go about their work. This often involves actually entering the mouth of the (as it must seem to them) monster to pick the insides and the teeth clean. There is an extraordinary understanding and trust between the species that means during the operation, the little fish are perfectly safe. Here are some examples, of which the very recent header image of a grouper named Arnold is quite outstanding.

Tiger Grouper + cleaner goby ©Melinda Riger @ G B Scuba copyGrouper, Black at cleaning station ©Melinda Riger @G B Scuba copy Tiger Grouper at cleaning station ©Melinda Riger @ G B Scuba copy Tiger Grouper being cleaned ©Melinda Riger @G B Scuba copy

It is not just gobies that attend the fish. Various species of shrimp also volunteer for the job.

Tiger Grouper with cleaning shrimps and goby ©Melinda Riger @ G B Scuba copy Grouper being cleaned ©Melinda Riger @ GB Scuba copy

Groupers are not the only species to make use of cleaning stations. Here is a dog snapper at the same cleaning station as the grouper in the header image. Below is a stingray being attended to.

Dog Snapper at cleaning station ©Melinda Riger @ G B Scuba copy

Southern Stingray with cleaning gobiesStingray, Southern with cleaning gobies ©Melinda Riger @ G B Scuba copy

GRAMMATICAL DIGRESSION There is this ‘thing’ about the correct use of the words ‘fish’ and ‘fishes’ in the plural form. The basic principle is simple: ‘fish’ where you are referring to several of the same species; ‘fishes’ where more than one species is involved. I don’t care. My policy is to use ‘fish’ as the plural on all occasions, so I don’t have to think about it. Pedants, look away now.






All photos: Melinda Riger, Grand Bahama Scuba


Goby (Cleaning) © Melinda Riger @ G B Scuba copy

Cleaning Goby (Melinda Riger)


A cleaning station is a place where fish and and other aquatic life congregate to be cleaned. This involves the removal of parasites both externally and internally, and is be performed by various creatures including, on the coral reefs of the Bahamas, cleaner shrimps and various species of cleaning fish such as wrasses and gobies. The process conveniently benefits both the cleaned and the cleaner.

Tiger Grouper being cleaned by Cleaner ShrimpsGrouper being cleaned ©Melinda Riger @ GB Scuba copy

Blue Parrotfish being cleaned (or tickled, from its expression) by a Cleaner Shrimp Blue Parrot Fish & Peterson Cleaner Shrimp ©Melinda Riger @ G B Scuba copy

  Black Grouper being cleaned by gobies – note the ones in its mouth Grouper at cleaning station ©Melinda Riger @ G B Scuba copy

Black Grouper at a Cleaning Station with gobies. Note the hook and line… Grouper, Black, at cleaning station (+ hook) ©Melinda Riger @ GB Scuba copy

Tiger Grouper being cleaned by GobiesTiger Grouper being cleaned ©Melinda Riger @G B Scuba copy

Gobies checking a hand for parasites….Cleaning Gobies copy

When a fish approaches a cleaning station it will open its mouth wide or position its body in such a way as to signal that it needs cleaning. The cleaner fish will then remove and eat the parasites from the skin, even swimming into the mouth and gills of the fish being cleaned.

“Clean me!” An amazing view of a Tiger Grouper at a CleaningStation with its gills wide openGrouper, Tiger - gills open at cleaning station ©Melinda Riger @GB Scuba copy

Grouper at a cleaning station over a spongeSponge : Fish Cleaning Station ©Melinda Riger @ G B Scuba copy

Remora clinging to a shark. For more on this unusual symbiotic relationship, click HERE383586_510314062323321_1002533913_n copy

 All photos: Melinda Riger of Grand Bahama Scuba, with thanks as ever