Usually seen in public aquariums, cuttlefish are likely to draw plenty of ‘oohs’ and ‘aahs’ from onlookers as they swim with their unusual long undulating horizontal fins. This reaction is particularly likely if the cuttlefish displays, sending waves of colour down the body with a rippling effect. They are also able to move by jet propulsion in the same way as an octopus.
The cuttlefish can be partly known to bird keepers, particularly those with budgerigars and similar. It is the cuttlefish bone that is used as it is a good source of calcium and also the birds seem to enjoy pecking at it.
Cuttlefish live in various areas of the world and can be large, 19″ (circa 48cm) or more, to small, 1½” (circa 4cm). Therefore, at least in most home aquariums, the larger ones are not suitable.
The colour displays that have been mentioned are achieved with the aid of chromatophores which are located in the skin. They are controlled by muscles and can activate with little delay allowing waves of colour to flow quickly across the body. It is reported that these colour patterns are a means of communication, indicating excitement, fear and also involved in mating.
Cuttlefish are predators and will continue their natural practices in the aquarium. Clearly prey is subject to the size of the cuttlefish, and includes crabs, shrimps, small fish, snails and even on occasion other cuttlefish. They have eight arms with two more that can be very quickly extended to grab prey.
Suitably sized cuttlefish could be considered suitable for the captive reef aquarium. Unfortunately there are two reasons why this is not so. The first is the lighting that is needed on reef aquariums to ensure the health and growth of the corals. This lighting is strong and can be a bank of fluorescent tubes to a halide system. Cuttlefish do not like this brightness. This may be because of their natural habitat situation and also perhaps because their eyes are well developed, possibly more so than any other invertebrate (other than in their own family group). The pupil takes a similar shape to a ‘W’ and can distinguish colour. Anyway, light levels in a reef system are too high, cuttlefish prefer medium to low light. The second reason is their predatory nature. Very often in a reef system there are small shrimps and/or crabs present and these will be a prey target, which is not going to please the aquarist. Further, many aquarists try to maintain high seawater quality by not having too many fish in their reef system, and one of the ways of achieving this is to house a restricted number of small fish. Again, it is likely that these fish will become a target.
It is possible to keep cuttlefish in two ways: in a species only aquarium or in a fish only aquarium. There will not be a problem with lighting as two fluorescents are sufficient, preferably arranged with electric timers into a ‘dawn/dusk’ sequence. If it is to be a species only type with more than one cuttlefish they should not be very different in size or there could be trouble. Mixing different types is also suspect and should be avoided. So ‘same species similar size’ is the guideline. The best and safest way, unless there is a lot of confidence, is to have one specimen – they are usually solitary in nature. If using a fish only system is being considered then the same comments about shrimps, snails, crabs and small fish apply, and in addition there should not be any larger fish that are aggressive or predatory by nature. In other words neither fish nor cuttlefish should be attractive as food to, or subject to aggression from the other.
As with most sea creatures the cuttlefish requires somewhere that is secure, such as a cave or the like. Rockwork will normally provide this but attention is needed during construction to ensure the cuttlefish is not too large to make use of the hideaway(s). The macro algae Caulerpa can be grown in the aquarium as well, which will enhance the aquascape and also be beneficial to seawater quality.
If keeping a cuttlefish is being considered, then the first requisite is that the aquarist is able to maintain successfully a fish only or captive reef aquarium. In other words, there should be experience in the maintenance of high seawater quality and healthy livestock. When a cuttlefish is located in a retailer it is important to have the creature correctly identified so that a check can be made on its eventual size (they grow quickly) for aquarium size consideration and also its temperature requirements (some cuttlefish require cooler seawater than is normal in a tropical marine system). It is also worthwhile seeing them fed, which will give the aquarist confidence and also the same food can be used at least to start. Cuttlefish will usually take to defrosted foods such as larger shrimp and fish.
Keeping a cuttlefish on its own or with suitable tank mates is more unusual than fish only and captive reef systems. It is possible, if there is the space, to have a captive reef and a cuttlefish in adjacent systems, perhaps interlinked for filtration purposes (subject to temperature considerations already mentioned). What a display! It goes without saying that maintenance, including routine seawater changes is required. Properly looked after, a cuttlefish can be expected to live to around three years or so, maybe more.