Clown shrimps (also known as Harlequin shrimps), Hymenocera picta, are some of the strangest looking marine shrimps you are ever likely to encounter! They have some unusual features (such as those massive flattened claws), bizarre colours and a remarkable food source - live starfish.

These shrimps naturally occur on coral reefs in the tropical Pacific (particularly around Hawaii) and Indian Oceans. In the wild they are often found in pairs, and many sources state that they mate for life. The female of this species is usually slightly larger than the male, and can be identified by the blue tips on the abdominal legs while males generally have transparent legs. This shrimp's maximum size is around 5.5cm (2"), although specimens collected from the Indian Ocean are typically smaller - usually reaching a maximum size of around 2.2cm (1").

Care and Maintenance

Clown shrimps can be rather shy, so an aquarium with plenty of live rock and rubble cover should be provided as this will give them the confidence to venture out into the open a bit more. These shrimps are quite sensitive to water quality, so you will need to ensure that you maintain this to a consistent high-quality "reef standard". Some people recommend that these shrimps are best kept as a pair - however I kept a single specimen and she (my specimen was a female as far as I could tell) seemed happy enough.

Feeding

Feeding a Clown shrimp in captivity is a major challenge due to their specialised diet of live starfish. In the wild these shrimps (normally working as a pair) capture and over-turn a starfish (often a Linckia sp.), and then proceed to eat their unfortunate victim's tube feet. There are many reports of wild Clown shrimps placing food items in the starfish's mouth so that it remains alive throughout the time it takes the shrimps to eat it, and this behaviour has also been observed in captivity. This is a very sensible strategy as a reasonable-sized starfish could feed a pair of clown shrimps for over a week, so keeping the victim alive throughout means that they can enjoy a continually 'fresh' meal!

With such a specialist food source, you can see how keeping these creatures at home can present a significant challenge. Many hobbyists in the USA feed live Linckia sp., Fromia sp. or 'Chocolate Chip' starfish to their Clown shrimps every week or two, and keep a supply of these animals in their sumps as a "living larder".

I'm not going to discuss the ethics of live feeding here as it such a complicated and controversial subject, but I will say that I personally find the idea of feeding such beneficial scavengers to Clown shrimps rather distasteful - especially when the feeding is so wasteful, as only the tube feet (and sometimes a limited quantity of other "meat") are consumed. Another disadvantage with this method of feeding is the cost, as a hungry Clown shrimp or two could eat their way through many larger starfish a year.

An alternative food source that is eagerly accepted by Clown shrimps are Asterina starfish. These small white starfish often arrive as stowaways on live rock or on corals, and they feed on algae and also eat the mucous many SPS and LPS corals produce. In the course of doing this they often cause considerable damage to the coral tissue itself, and their presence in a reef tank is therefore undesirable. They are able to reproduce rapidly and can quickly cause havoc in a reef tank with a large coral population. If you have a population of these nusciance animals and need to dispose of them anyway, the addition of a Clown shrimp could be a useful and natural method of doing so.

Asterina Starfish. Photo borrowed from Wetweb Media

Given the small size of these starfish, a Clown shrimp would need a large and regular supply of these pests to keep it well-fed. However the shrimps seem to eat the entire starfish, so the feeding process is nowhere near as wasteful as feeding with the larger varieties of starfish. Many reefkeepers actually acquire a Clown shrimp to eat all of the Asterina starfish in their reef tanks, before passing the shrimp on to a fellow reefkeeper to 'clear' their tank. A Clown shrimp might have to be re-housed every few weeks/months as the food supply in each tank it stays in is exhausted. But to keep a Clown shrimp in one system long-term you would need to provide a regular supply of Asterina for it to eat...

Propagating Asterina sp. Starfish

As most starfish are able to re-grow missing legs with relative ease and speed, there is nothing to stop you propagating these nusciance animals as an on-going food supply. To propagate an Asterina, all you need to do is capture a suitably-sized starfish with tweezers and carefully and cleanly cut it in half with a sharp scalpel or scissors, before returning the two 'halves' to the tank. Each 'half' will then rapidly re-grow the missing legs and body tissue, and thus you can double the population of Asterina in a relatively short space of time. Although this sounds rather gruesome, it does not seem to hurt the starfish at all, and they go about their business normally while the missing limbs re-grow.

My reef system consisted of several different tanks linked together and this design came into it's own when I was keeping my Clown shrimp. I would keep the shrimp in one tank while she 'cleared' it of Asterina, whilst rapidly propagating the populations in other parts of the system. When food had run out in the tank the shrimp was in, I simply moved her to the next tank and re-commenced propagating in the tank she had just vacated. By moving her around regularly I was able to sustain a regular food supply, but the Asterina population never became too large in any part of the system. In systems containing a large refugium or sump, these areas would work extremely well as Asterina 'farms', and a regular supply of starfish could be transferred to the main tank for the Clown shrimp to eat when required.

Some Final Thoughts on Long-term Care

I would urge you to consider very carefully whether your system could support one of these beautiful creatures in the long term as they are voracious eaters! It should be noted that, starfish aside, these shrimps are considered to be completely reef safe. However, it would be unwise to keep these shrimps in aquariums containing Sea Urchins as these also have tube feet, and may prove to be too much of a temptation to a hungry Clown shrimp...

Before buying a Clown shrimp it would be wise to try propagating Asterina for a few weeks, just to make sure you are able to successfully maintain a regular supply of these starfish - my Clown shrimp ate up to 10 small Asterina a day! Of course if you are successful with this, you will definitely need the services of a Clown shrimp to control the population of Asterina that you have just created!!!