About Invertebrates

Following on from the development of marine fishkeeping in the relatively sterile environment of the fish-only aquarium, the “reef-style” aquarium made its appearance some years ago. By today it would appear that most home marine aquariums incorporate at least some invertebrates into the décor. Quite often the inclusion of such décor pieces is the prime objective of the aquarium, with any added fish featuring as secondary attractions. A lot of thought is required as to how the miniature coral reef is to be constructed within the confines of a home aquarium. In nature, inverts will fight one another with stinging cells on extended polyp “arms”. In this way they are able to reserve their space on the reef without being squeezed out by an expanding adjacent colony. If this type of invertebrate animal is set beside another natural “enemy” too closely in the aquarium, they will engage in combat to the detriment and eventual destruction of one or both.

Marine Aquascape Marine Aquascape











Sessile inverts, like corals, sponges, tunicates etc, are often the natural diet of many reef fish, so it would be disastrous to introduce such species of fish into a home reef aquarium. Similarly some of the mobile invertebrates, like crabs, shrimps, shellfish, worms, etc are eagerly relished as tasty morsels by some fish species, and must also be considered when the fish are being assembled for inclusion. Suitable rocks will usually be chosen to form a base on which the “reef” may be constructed.

Like the “fish-only” marine aquarium the reef tank requires excellent filtration, and something along the lines of what has been described in the text of our “Marine fish-only” page will be needed. The lighting is a more important consideration, as it will play a big part in the success or otherwise of the sessile invertebrate pieces. Most hard corals and anemones need to have strong lighting to support their life processes and LEDs are one recommended type to have over the reef aquarium for maximum effect. A bank of high intensity output fluorescent tubes provides an alternative lighting set-up. However, not all the inverts will appreciate being exposed to the full glare of such lighting, as in nature they favour overhangs, rocky niches, and the more shaded areas of the reef away from direct sunlight, and should be placed accordingly with thought in the reef aquarium.

As with any marine aquarium the water quality is of paramount importance, and regular part-water changes are vital to the success of the reef tank. Special watch must be kept for any signs of deterioration of the sessile invert pieces, as they will pollute the water quickly and to a serious extent if allowed to remain and die in the heated seawater. Maintaining the essential perfect water chemistry while addressing the feeding needs of the population within the aquarium, demands a careful balancing technique which careful trial and error will perfect. Most corals, sponges, tunicates, and other sessile invertebrate animals feed by filtering the water and removing suspended nutrients from it. When applying liquidised foods for this purpose it will be necessary to reduce or turn off the filtration for a short time to give the inverts a chance to gather in the particles before the filters do. Shrimps and tiny crabs will scavenge the nooks and crannies inaccessible to the fish, but their intake will be quite restricted, and it is not practical to rely on these tiny creatures to clear up gross overfeeding.

The need to mature the filtering system of a reef aquarium thoroughly and with care, cannot be over-emphasised. Please check out our “Marine aquarium – fish only” page for more information about setting up a marine aquarium, or better still visit the shop for advice and guidance.