Fish and False Representation – the Firefish

There are many fish on the coral reef, from small to very large. Some could hide quietly. Others cruise the rocks in a particular area, alone or in a shoal, and take algae. Others are omnivores and eat more or less anything they can cope with. Nothing new there then, these fish are what they are.

Some fish falsely present what seems a tasty morsel to others and when the others come close they become the tasty morsel. This isn’t the false representation being considered here though.

A beginning aquarist who has carefully researched will be very careful about what is picked to go in their marine aquarium. There are warnings about inexperience and choosing a fish because it’s so pretty and impressive. It could grow too large, it could be a predator or it could simply be too difficult to maintain. There is a fish that will ring alarm bells in the new aquarist’s educated mind as it is beautiful, aquarium sized and delicate looking – is this to be avoided, what a shame.

But no, that is not the case with this fish. The fish comes from a large group, the Gobies. In appearance it seems delicate and probably hard to maintain – it is not difficult but easy to keep, peaceful and very hardy. The proper name is Nemateleotris decora, generally known as a firefish. Full size is 3.5 to 4ins (circa 9 to 10cm). There are other firefish very similar (such as Nemateleotris magnifica).

First of all, though the firefish is very hardy and easy to keep there are qualifications to this. Well of course there are, nothing is that straightforward.

The fish can be easily bullied and if it is it will go into a hideaway and not be seen very much. Its feeding routine will be disrupted, stress will be constantly present and health will suffer. The fish is not suitable for a fish only system even if there are plenty of rocks present. Fish only systems tend to house larger and often more aggressive fish. The only real home for a firefish is a reef system which can be small to very large. Corals etc will not be harmed.

The reef system strangely enough has a built in reef which provides many choices of cave and crevice for the firefish. Once a hideaway has been chosen the firefish will be more settled and make a regular appearance, often generally maintaining a midwater position as it watches for edible material to appear. It’s very important that more aggressive fish are not present, with a reef system this is easily achieved as there are many non-aggressive fish available. As far as the number of firefish that can be kept, this does require some caution. It has been suggested that the firefish is happy in a reef system as small as 10 gallons, but there is a danger that if more than one firefish is present there will be trouble. This is to do with territory. In such a small aquarium a mated pair of firefish should be the only multi introduction. In much larger reef systems two unmated firefish could be introduced simultaneously as there will be enough area for more than one territory.

The firefish is a carnivore and will take food from the seawater column or rocks. Feeding is not difficult as the fish will take a variety of foods, flake or frozen.

There is one more potential problem – the firefish is reportedly a good jumper. This could be an attempt to get away from aggression? It is suggested that the aquarium has glass covers, or better a thin mesh net fitted within a very light frame for easy removal.

So the firefish has all the atributes of a wonderful addition to the population of the reef aquarium. It is peaceful, hardy, easily fed and very beautiful. It will never grow too large. It will not harm corals. The fish looks very delicate but that is false. Provided the aquarist does not have aggressive fish all should be well.



  1. Good post. I learn something totally new. I’m sure it will always be interesting.

  2. Always pleased to read that kind of comment.

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