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Related Articles: Recruiting Marines; Learn the basics of stocking a reef tank with this guide to biotope setups by Bob Fenner,  Marine Livestock Selection, Collecting Marines, Quarantine, Quarantine of Corals and Invertebrates, Acclimation, Acclimating InvertebratesMarine Life Use in Ornamental Aquatics

The Best Livestock For Your Reef Aquarium:

Reef Livestock Selection Considerations

Bob Fenner

Gotta big reef set-up?

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner

You might think with all the experience (most "reefers" have graduated from extensive freshwater and fish-only marine systems), large costs (hundreds to thousands to tens of... ), and expertise involved, the world of reef aquarium keeping would leave out/exclude inappropriate livestock offerings and mixings by the industry and hobbyists. Such is not the case. Unfortunately for the life and consumer, much of what is available and thrust together just doesn't cohabit very well or long.

The 'reasons' for this apparent ignorance & apathy parallel the 'lesser' realms of captive aquatics keeping, but their solution should be much more expedient. Because reef aquarists generally have comprehensive backgrounds with aquaristics and science, a great deal of time/money/general resource committed, and are so keenly involved in their interest, much progress is being made in inching up the learning curve of selection and care of captive reef life. Concurrently tremendous benefits are accruing from the demands of the trade and consumers for optimizing the health of reef livestock at their sources: culturists and wild-collectors are more and more compelled to develop kinder and gentler handling and shipping technologies.

All this being said, your role in providing 'pressure' in what gets collected and how it is processed is predominant. Where your money is cast directly determines which specimens of what species make their way to stores and reef set-ups. Never forget this.

(Images 1,2: A tank you can really "get into", a fish-only super-hex, the Tetra pavilion aquarium at the 1996 Interzoo, Germany. The alternative to dead, bleached coral skeleton/decor, a full blown reef set-up in Oah'u, Hawai'i at the Waikiki Aquarium. Folks who think dead corals are attractive probably find human skeletons beautiful by comparison as well.)

Choosing Well: A Plan

Per your particular systems parameters such as its size and shape, circulation and filtration, light intensity/quality/duration it will hold a given mix of organisms... Which types and how many? First off, the usual admonition concerning crowding here: don't. The vast majority of 'problems' with reef livestock are due... no surprise, not to feeble or lack of appropriate gear, testing, or other maintenance protocol, but to placing the wrong, and too much life together. The more mis-matched and concentrated that bio-blend is the more, faster and dire the difficulties become.

To wit, and though most folks will not do so, you should prepare a written Stocking Plan of what life, in what numbers and order you intend to put in your system. I know (I've been in the pet-fish industry all my semi-adult life) that "the dealers only have such and such on hand", and, "but it was A) so good looking, B) on sale, C) going to be bought by someone else... Please, spare me, the livestock and yourself the aggravation of putting together your reef microcosm based on such criteria.

Follow along with me here as you start to make that checklist of who's going in, in what order based upon your working knowledge of the following parameters and that life: Size, Growth Rate, Temperament, Diet, Light and Circulation.

Size: Yes, It Does Matter

Larger life, especially non-sessile forms (i.e., not attached) are less desirable for reef aquarium use on several counts. Bigger, more mobile organisms utilize more food, and produce more wastes. The latter are problematical in their removal and contribution to noisome algae growth. The former points to behavioral difficulties.

By and large, all marine species are to a degree "aggressive", and this tendency is positively correlated with size... larger animals are "meaner" toward smaller ones. Hence, you should procure animals at small-enough initial sizes and deal in species that will stay small-enough for the system and their tankmates.

(Image 3: Good looking, and not a coral eater, the Naso Tang, Naso lituratus, gets way too big (over two feet in the wild) for most all hobbyist reef systems)

Growth Rate:

Related to size matters, rates of growth are also an important consideration. Think about this in terms of resource partitioning in the wild; utilization of physical and biological resources by and within competing species. The social dynamic of your system is an ever-changing process that calls for careful planning. With some animals growing faster than others, who gets to use which space and eat/browse which foods often leads to territorial skirmishing... Add to this your placing new livestock at times and you can understand how "war" can and does break out.

You want your livestock to either grow in lock-step with each other, or otherwise pose little friction in the animals' relations with each other. Remember, your success as a reef aquarist is concurrent with how much life: biomass, growth, food, overall processing that goes in/out of your captive aquatic system. The less and more controlled to optimize and stabilize water quality, the better.

(Images 4,5: "And they're off!" In a race to see who can grow fast enough to eat the other (both starting at a few inches long), the Miniata Grouper, Cephalopholis miniata, can win by a gulp within a year over the Coney, Cephalopholis fulvus), though they get to 18 and 12 inches in length respectively... given time.)


Depending on size, growth rate and general understandings of the "average" and "standard deviation" of "meanness" of a given species, you can make an educated guess as the likelihood that your intended menagerie will coexist or not. Most all animals with a mouth big enough to swallow their tankmates will do so (bass example), but even small-mouthed species (like triggers, puffers ex.s) are contraindicated as they utilize their powerful jaws to bite off pieces of other animals.

(Images 6,7 Which would you rather have in your tank? An eight inch Undulated Trigger, Balistapus undulatus, or a two inch Hawaiian Spotted Sharpnose Puffer, Canthigaster jactator? For me, make it the Trigger, if it's one from the Indian Ocean or Red Sea. Most, I repeat, the majority of the non-Pacific members of the species leave invertebrates alone. The same cannot be said of those tiny Tobies (subfamily Canthigastrinae). They're always biting their tankmates.)

Often, members of the same family, within the same genus, and of the species are least likely to get along. But this is not a hard and fast rule. In other cases, closely related forms are best kept in pairs, trios and larger assemblages.

(Images 8,9 The more the merrier if you have the room,

Rogue individuals of even the usually mellowest species should be mentioned. There are incidences where such terrors develop and bully and tear up most all other life in their/your system. The only way to guard against such acts is... day to day careful observation of your livestock. Sometimes, catching, corralling, temporarily moving these bullies will change their behavior. I have witnessed social "readjustment" by the addition of other more aggressive tankmates and moving the decor/territory around as well. (ex.s. Basslets, Gobies...)


Though there is a huge variability in the personal habits of many animal groups, most folks who keep reef tanks include stinging-celled life (corals, sea fans, anemones, corallimorphs, zoanthids...) and therefore exclude outright corallivores. By definition we can list and exclude the worst perpetrators who are likely to eat their cnidarian tankmates, but you should know that reefs, captive and wild, are not such white/black worlds.

Obviously, all the animals found in and on the reef do "get along" with stinging-celled life to a degree. The line can be drawn as to who is likely (obligate) to munch on corals and such and who is probably not, but there is a vast nebulous group in-between that does nibble occasionally and if pressed for lack of other food (and/or attention) will sample their sessile tankmates; possibly to death.

As a general rule, you want all your captive charges to eat (if they do) a mix of foods you can provide... in small quantities, to limit growth, waste production, and agonistic behavior... And to definitely not eat each other. (example, Scarids and Corals)


When giving talks at hobbyist conventions it always strikes me as strange that the attendees not realize how very different natural reef micro-environments are... current, predator-prey relations, light factors and more severely delimit the types and viability of life forms found in one area to another.

With experience, reefers learn general husbandry strategies like placing new sedentary livestock in deeper, darker areas of their systems at first... moving them to brighter surroundings on acclimation, till the specimens seem "happy" in their placement.

Within reason, and given large system size, plenty of rock decor to provide subdued lighting habitat, most all aquatic life offered in the trade can be kept under a standard lighting regimen. Can. (examples, Distichopora, Dendronephthya, Xeniids, Lions)


Once again, practically speaking, no private or public aquarium is overly-circulated. However, the type and steadiness of flow can be problematical with many sessile invertebrates. By and large, water flows in a system should be complete (you want all areas of the tank to get moved around), but these flows should be non-linear (not one way, as in a powerhead constantly blasting across the top or side of a stationary animal), and if possible chaotic in their flow path and strength; mimicking the effect of tides and waves in the wild.

So, you might concentrate on animals that occur and have been collected from relatively calm reef flat areas (where many corals and most Live Rock is collected), or the ferocious turbulence of a windward fore reef, or a mud flat/bay setting (examples of tubeworms and ceriantharians).

Putting This All Together: Biotopic Presentations

You've no doubt heard of biotopes; a kind of cross-section representation of the living and non-living components of a given (micro)environment. For reef-keepers the principal components of assembling a biotopic presentation are listed in the headings above. You can and should "slant" your system toward a specialized format: tropical, cooler/cold water, geographical location (e.g. Red Sea, Caribbean), peaceful/medium/aggressive, community/species accented... Such systems are not only more "natural", they're easier to maintain/keep and (I'm almost afraid to state so) educational.


Yours, of course, not your livestocks. Do take your time. Plan out your system. The tank, its placement, the mechanicals and controllers; details like the source, curing of your Live Rock (and possibly Sand)... and your livestocking. And execute against this plan in a systematic fashion. You are the grand arbiter in this scheme and you need to take your time. Setting up a system at first requires a few weeks to months to effectively "cure" the system ahead of placing specimens (other than Rock and Sand), and really reaches its zenith in six months to a year or more. Take your intelligent time; it's necessary and makes the whole experience that much more worthwhile.

A Beginning:

Of a certainty, knowing and practicing which species are best for reef use, and how to sort through their best representatives at a dealer's is important, but only a small part of being successful as a reef aquarist.

Properly planning and setting up a system, ensuring that the gear and your maintenance retains optimal and stable conditions, as well as the unknowns of mixing and matching your livestock per their physical needs and biological dynamic is likewise critical.... As are undercrowding, selective/appropriate feeding and patience.

Read all you can, engage yourself with other aquarists of similar dreams, and above all carefully observe your livestock for signs that all is well or amiss.


 Bibliography/Further Reading:

Small Marine Aquariums
Book 1: Invertebrates, Algae
New Print and eBook on Amazon:
by Robert (Bob) Fenner
Small Marine Aquariums
ook 2: Fishes
New Print and eBook on Amazon: by Robert (Bob) Fenner
Small Marine Aquariums Book 3: Systems
New Print and eBook on Amazon:
by Robert (Bob) Fenner

Allen, Gerald R. & Roger Steene. 1994. Indo-Pacific Coral Reef Field Guide.378pp.Tropical Reef Research, Singapore.

Ates, Ron. 1991. Fishes eating corals. FAMA 7/91.

Blasiola, George C. 1986. Marine fish compatibility. FAMA 8/86.

Brawer, Marc. 1972. Compatibility. Marine Aquarist 3:1(72) Jan-Feb.

Brelig, Allen. 1989. Selecting compatible saltwater fish. Part I: Developing a plan. Part II: Selecting specific fish. FAMA 10,11/89.

Burgess, Warren E. 1978. Selecting marine fishes. TFH 1/78.

Burgess, Warren E. 1978. The right size fishes. TFH 2/78.

Delbeek, J. Charles. 1993. Stocking your first reef aquarium for success. AFM 5/93.

Fenner, Bob. 1989. Successfully selling the popular marines. Pets Supplies Marketing 1/89.

Fenner, Bob. 1989. Selling compatible marine species. Pets Supplies Marketing 10/89.

Fenner, Bob & Cindi Camp. 1990. The most appropriate marine fishes for aquaria; retail selection, display and maintenance. FAMA 3/90.

Fenner, Robert. 1995. The continuing use of cyanide in the collection of marine fishes. FAMA 2/95.

Fenner, Robert. 1998. The Conscientious Marine Aquarist. Microcosm, VT. 432pp.

Fenner, Bob. 1998. Reef Matters: How to go about planning and picking out marine livestock. Parts 1-4, TFH 5-8/98.

Fox, Dale A. 1992. Some notes on selecting marine species. TFH 7/92.

Gosliner, Terence M., Behrens, David W. & Gary C. Williams. 1996. Coral Reef Animals of the Indo-Pacific. 314pp. Sea Challengers, Monterey, California.

Guerra, Manuel III. Compatible fish for reef tanks. FAMA 7/90.

Hemdal, Jay. 1988. Fishes for the home miniature reef. SeaScope v.5, Spring 88.

Hunt, Philip. 1998. Six of the best fishes for the reef aquarium. TFH 2/98.

Hunziker, Raymond E. 1986. The marine aquarium made easy. Part 3:Fishes. TFH 12/86.

Maki, Michael. 1992. How-to select a healthy marine fish. FAMA 10/92.

Michael, Scott W. October 1994 on. Fishes for the marine aquarium. (An excellent monthly series covering selection, care and natural history. Aquarium Fish Magazine).

O'Malley, John. 1989. Choosing saltwater fish. AFM 2/89.

Paletta, Mike. 1999. Unexpected fish for the reef aquarium. Not typically thought of as" reef safe". AFM 5/99.

Robertson, Graham C. 1977. A beginner's fishes. Marine Aquarist 8:3 & 4(77).

Shute, J.R. and John Tullock. 1995. Difficult species. TFH 1/95.

Tullock, John. 1998. Environmental issues and the marine aquarium hobby. Part Two: Adaptability of fish to aquarium life. FAMA 2/98.

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