Selecting Invertebrates and Fishes

Ultimate Secrets To Saltwater Fish

Idiot Guide To The Marine Aquarium

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The options may seem endless when it comes to all the saltwater fishes and invertebrates you have to choose from to stock your tank. However, by making the following considerations you can make selections that work well for your tank.

Types of Fishes

The commercial trade in coral reef fish provides us with comparatively few large groups into which virtually all species can be sorted. Looking at potential aquarium inhabitants in terms of which group they belong to makes more sense than trying to treat each variety as unique. Thus, we can identify five basic types of marine aquarium fish:

1. Large, aggressive predators

2. Peaceful community fish

3. Bottom-dwelling scavengers

4. Algae and plant eaters

5. Oddballs

Large, aggressive predators and oddballs usually do best if provided with a tank to themselves. Representatives of the other three groups can be combined in one tank to create a community that reflects a natural biotope.

Taking Size into Account

Some fish are just naturally better aquarium fish than others. A good aquarium fish should remain relatively small at maturity. Space and money constraints limit aquarium size. The size of the tank defines the upper limit on fish size within it, obviously. Custom-built aquarium systems, of course, can be any size your budget permits, but most people reading this book will be considering systems holding 1 50 gallons or less. That translates into a six-foot-long tank, the largest most stores have in stock. Unless you intend to exhibit only one or two fish, four inches is about as large as any individual specimen should grow to be. Many possibilities exist in this size range, although as a rule saltwater fish grow large.

That said, we won't rule out larger fish species in the model designs presented later. We'll simply use only one fish as the focal point, or recommend a community of two or three species suitable for a really large home tank.

Assessing Adaptability

A good aquarium fish should also adapt readily to captive circumstances. This would seem obvious. Yet, plenty of fishes are doomed to an early death simply because their ecological requirements are difficult or impractical to satisfy in a home aquarium. Some species will only take live food. We have already mentioned butterflyfishes that feed exclusively on coral polyps as an example. Some fishes just do not ship well. They

Bringing Out the Best in Saltwater Aquariums 47

Bringing Out the Best in Saltwater Aquariums 47

arrive at the dealer in poor condition and never manage to recover. While I have not ruled out the use of wild-caught fish in the model designs presented later, I encourage you to begin with selections from the many tried-and-true varieties that are available from hatcheries.

Considering Coloration and Behavior

A good aquarium fish should either exhibit brilliant coloration or possess some interesting behavioral quirk to justify the effort required of the aquarist. Some marine fishes sport beautiful colors as juveniles, then grow into drab, gray adults. On the other hand, the various species of lionfish are mostly brown and white in color, but their elaborate finnage and graceful movements endear them to aquarium keepers. Behavior involving specific relationships can form the basis for a fascinating small aquarium. Nowhere else on Earth does symbiosis flower as it does on the coral reef.

Symbiosis literally means "living together." Two different species (and sometimes more) are characteristically found together. The exact relationship may take many forms. Perhaps the most widely recognized example is that of the clownfish living among the tentacles of a host anemone. Of greatest importance to the life of the reef is the symbiosis between corals and photosynthetic algae. Known collectively as zooxanthellae, the algae live within the tissues of certain corals and participate in all manner of important metabolic functions. Keeping the zooxanthellae happy is the prime goal of any minireef aquarium design.

Types of Invertebrates

Invertebrates, although they appear in great profusion in the aquarium trade, can, like fish, be sorted into relatively few groups. These are:

1. Photosynthetic invertebrates (except clownfish host anemones)

2. Clownfish host anemones

3. Utilitarian invertebrates

4. Other nonphotosynthetic invertebrates

Each group has a role to play in the minireef tank, while fish-only aquariums are usually limited to the last two groups.


Seaweeds can add the perfect touch to a saltwater aquarium. I broadly define seaweed as any desirable algae visible to the naked eye. My definition therefore includes encrusting, calcified varieties known as coralline algae, as well as green, leafy types that resemble terrestrial plants. Depending upon the availability of light, seaweeds figure in the ecology even of fish-only aquariums.

48 Saltwater Aquarium Models

48 Saltwater Aquarium Models

Captive Propagation

Far more varieties of invertebrates and seaweeds come from captive propagation than is the case with fish. Seaweeds have been cultivated for centuries. Techniques for their commercial production have been adapted for the aquarium varieties. Many species of invertebrates can simply be cut into pieces, and each one will regenerate a completely new specimen. Analogous to the production of horticultural varieties, "fragging" invertebrates has become something of a cottage industry among dedicated reef enthusiasts. Even organisms with more elaborate life cycles, such as giant clams, are hatchery produced.

One of the most useful saltwater aquascaping materials, live rock, is farmed by depositing quarry rock at sea, and coming back in a year or so to bring it up again. Live rock harvesting is prohibited in some places and allowed in others, providing the market with both farmed and "natural" types.

I urge aquarists everywhere to seek out captive-propagated fish, invertebrates, seaweeds, and live rock, and to look for collected specimens that have been harvested sustainably.

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Aquarium and Fish Care Tactics

Aquarium and Fish Care Tactics

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