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Fish or Corals?

Fish only or corals?

Marine aquariums can be divided into two categories; 'reef' and 'fish only' (or 'non-reef')
A reef aquarium can house a wide range of fish and invertebrates such as corals, crustaceans and other creatures whilst a 'fish only' tank is only suitable for fish. Strictly speaking, a 'fish only' tank is capable of housing some invertebrates depending on the type of fish you have, but the choice will be limited. Whilst the obvious choice might be a reef tank, there are a number of considerations to take into account before you decide.

marine lionfish

Why have fish only?

Some of the popular marine species we see for sale, such as lionfish, pufferfish, and triggerfish, may not be suited to an aquarium containing corals and other invertebrates as they are likely to eat or damage them. If we want to keep these fish we are limited to a fish only or non-reef tank. Apart from being able to keep a wider variety of fish, a fish only tank is a lot cheaper to set up and run, is easier to maintain, and requires less fish keeping knowledge. For beginners, a fish only tank might therefore be a cheaper and easier entry to marine fish keeping.

Extra equipment needed for a reef tank

To set up a reef tank, in addition to the standard equipment needed for a fish-only tank, you will need a few extra items, of which pumps and lighting are the most important. Many corals will feed from particles in the water as well as energy obtained from light (via algae cells growing in their tissues) and need both in abundance to thrive. In shallow tanks, high intensity (often called T5) tubes can provide enough light for the majority of easy to keep corals, but for deeper tanks high powered halogen or halide lamps are required. To get enough water movement for feeding, (and also to prevent debris from settling on corals, which can damage them) you will need to use several powerheads, or pumps, situated in various places and at different angles. In addition to extra lighting and water movement, a reef aquarium will also require a closer check on water conditions and may require the addition of calcium, extra trace elements, and specialist foods for some corals.

hermit crab

Can I change from fish only to reef?

It is perfectly possible to upgrade an aquarium from fish only to reef, but this needs to be thought about from the beginning. Throwing away your existing light unit to install a more powerful one is an expensive waste and pumps will need a reasonable amount of access through the hood for cables. If you might want to upgrade later, make sure that the tank you purchase can be easily upgraded and check to see how much this will cost – you may save money by purchasing a tank which is more easily upgraded. It would also be wise to stick to livestock which is suitable for a reef tank so that you are not left with problem fish when you upgrade.

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