There are Goatfishes in tropical to temperate seas in shores and reefs of Asia, Europe, North America and Australia. They are common as individuals, small groups of single species and occasionally shoals of dozens to hundreds of individuals.
Some goats achieve a good eighteen inches in the wild, most aquarium ones stop at about six inches.
Selection: General to Specific
Picking out a healthy specimen is a breeze with Goatfishes; they're either "A" number one grade, ready to go; or flat out dead or dying. Look at the specimen/s on hand; they'll be either swimming or huddling together along some structure, or on their way to fishy-heaven with off color (typically red) blotching with X's on their eyes.
Collecting Your Own
Can be done if you're in the area; via small hook and line, baited with a meaty treat, or chased into a barrier/mist net.
Environmental Conditions: Habitat
Any "fish-only" system of adequate size will do; I would provide a good ten gallons of space per each small specimen, twenty or more for every medium to larger one.
A word of caution re covering your system with these fishes; they jump; I mean, like Polaris missiles. Keep it covered.
And why not a Goatfish in your fish and invertebrate, or full-blown reef tank? I have seen this done with very small Mullids, and with definite benefits in terms of keeping the substrate loose, and definitely removing unwanted bristle worms, small mantis shrimps, et al.. The problem enters when and where the goatfish keeps eating... as in your desirable (read that as expensive) livestock. Forewarned is forearmed, so beware. It is my opinion that these fishes are great for aquariums, but just fish-only aquariums.
The group as a whole are very undemanding; standard marine aquarium conditions suit them fine.
There is one other aspect of goatfish biology that merits mentioning, the strange case of their ichthyoalleinotoxic property. Yes, these fishes are known to be hallucinogenic! No, I'm not making this up, or smoking goatfish or anything else; the goatfishes do induce odd sensory perceptions during certain seasons, and are consumed knowingly. Not only have I read of such goings on, but have munched on them myself in the Yucatan (Mexico), Moorea (French Polynesia), and the Visayas (Philippines), among other places I can't seem to recall, with subsequent "tingling" feelings and a sense of general self-satisfaction. Hmmm.
Should be vigorous, not only because of goatfish activity and waste production, but to supply adequate oxygen and removal of dust and mulm kicked up by barbel and mouth digging.
To keep a Goatfish happy you will want an open area for foraging. For both your sakes, supply a suitably substrate; not too fine or given to dissolving easily so that the goats stirring and digging don't cloud the tank.
Placing your Goatfish/es can be as unceremonious as you want it to be; many wholesalers dispense with regular dip and quarantine procedures with these fishes; I would not. Just to make sure you're not slipping in an infectious or parasitic disease, a freshwater dip of a few minutes duration will serve to eliminate most transmissions.
For the most part the goatfishes are so fast and agile that wannabe predators don't have a change; alternately, they can be trusted to leave other livestock alone with one caveat; everything smaller than their curious mouths, will be tried... These animals are carnivorous/omnivorous, and will try to eat any ingestible fish, invertebrate, rock(!).
Typically Goatfish are found in close association with other foraging reef fishes, the others attending as their digging "pal" unearths the next meal. By and large Goatfishes are not agonistic toward other too-large-to-swallow tankmates or conspecifics.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
How do you tell when your Goatfish is dead? It's not eating, or looking for food. Seriously, there are no more eager feeders than the Mullids; they greedily accept any and all forms of prepared and fresh foods. Thank goodness that the "goats" typically live near the bottom, otherwise your other livestock would likely wither from lack of nutrition.
Should your Goatfish become more of a "hog" (apologies to Bodianus owners), you might want to develop a feeding strategy of pushing a food item on a "stick" down to the Goat/s while proffering other food elsewhere for the rest of your aquatic charges.
Disease: Infectious, Parasitic, Nutritional, Genetic, Social
The family is remarkably disease-free, and typically succumbs last to large-scale infections in a system. They are however quite susceptible to isopod infestations. These "pill-bug" relatives are grayish crustaceans frequently found on the backs and inside the mouths of newly imported specimens. Should you discover some of these Rolly-Pollies, they can be easily removed via sturdy tweezers.
The Goatfishes, to know them is to love or at least appreciate them. Looking for an interesting cleaner-upper to keep things lively in your tank? Search no further than the Mullids; they're tough, beautiful and easy to keep.
Burgess, W.E., H.R. Axelrod & R.E. Hunziker III, 1990. Atlas of Aquarium Fishes, v. 1, Marine Fishes. T.F.H. Publications, NJ.
Herre, A.W. & H.R. Montalban, 1928. The Goatfishes, or Mullidae, of the Philippines. The Phil. J. of Sci. v. 36, no. 1, pp. 95-137.
Michael, Scott W. 1997. The Goatfishes. Put a Goat in your tank. AFM 1/97.