"If wishes were fishes, we'd all have full tanks", one of my few (if any) original statements. And, if I had one large pet-fish wish it would be that hobbyists would "cast their votes" for cultured (read that tank bred and reared) livestock as opposed to wild-collected. Such choices make imminent sense even disregarding possible savings, wear and tear on natural stocks, environments... Captive-produced fishes and non-fish specimens are hardier, more adaptable to aquarium conditions... liable to accept all forms of prepared foods and live longer, happier, more out-going lives in your systems than ones caught out of the seas.
An extreme example of this differential survivability is the subfamily of damselfishes we call clowns. This group of 28 species has an absolutely dismal survival record being collected from the wild... contrasted with phenomenal vitality of captive-produced stocks.
Incidental Collection Mortality:
Reliable numbers are as rare as "hen's teeth" in the way of losses along the chain of custody, collection, holding, shipping, re-bagging... of wild marines to their final homes. However I would hazard a guess that easily half of Clownfishes succumb from collective stress, mishandling and parasitic complications traveling the few to several days it takes to go from the reef to retailer. It is rare to visit a marine livestock wholesaler and not view wild clowns in various degrees of dying.
Dying from what? Who can state how much a negative influence being caught away from ones anemone is? All clownfish species are obligate mutualistic symbionts with species of large sea anemones in the wild. Of the multiple insults of rough netting, crowding with other livestock, variable and diminished water quality, starvation (most marines are not fed in anticipation of sale, transit)? Compared with tank-bred specimens (some of which will actually spawn in the bag while being moved), many wild clowns are lost while being shipped. Add to this induced stress the presence and proliferation of external and internal parasites and you can understand why so few wild-collected Clownfishes live for long in captivity.
Clownfish parasite loads include the "usual suspect" twin scourges of marine aquarium keeping: Cryptocaryoniasis (white spot or marine ich), and Amyloodinium (velvet), as well as a few other protozoans, seen all-too often on other wild-caught fishes. Additionally, there is a protozoan infestation so closely associated (and common) with Clownfishes that it's often called "clownfish disease". This prevalent external parasite commonly occurs along with the stress of collection and importation, but can occur consequent to any trauma.
Not to leave out their mention, there are internal worm diseases of Clownfishes (Wilkerson (1998) restates a figure of internal worm infection of 70-85% in wild-captured Amphiprionines.), various nematodes, tapes, thorny-headed parasitic species... And isopod crustaceans, mainly secondary bacterial and true fungal complaints as well. For the most part these are not of primary concern to aquarists dealing in wild stocks, as the former are largely untreatable and the latter avoidable by diligent quarantine and system maintenance.
Brooklynellosis, Not Related To New York:
The condition of having an infestation of the protozoan Brooklynella hostilis. Characterized by its shape (oval with a dorso-ventrally flattened anterior end), small size (56 to 86 by 32 to 50 um), mode of transport and morphology (covered by small cilia) on a microscopic level. Symptomatically, host fishes appear to bear skin lesions, a thick whitish mucus coating (Brooklynellosis is also known as "turbidity of the skin" disease), gasp near the surface (the gills are said to be the first attacked), are lethargic, refuse to eat, lose color, often succumbing with hours to a day or two after being initially diagnosed. Importantly, many of these symptoms are shared with other parasitic conditions like marine ich, and even more significantly, unlike most marine maladies that can be cured with copper treatments, Brooklynellosis cannot.
Specific identification requires microscopic examination of the parasites, made by wet-mount of mucus, skin from infected fishes. Brooklynella are heart- or kidney-shaped of 56 to 86 by 32 to 50 microns. They present a large oval macronucleus and several micronuclei and other endoplasmic organelles as well as a prominent adhesion organ on the posterior-ventral area.
Host Specificity, Not Clowns Alone:
This condition is most associated with Clownfishes, but is recorded from other fish groups. Angelfishes, Jawfishes, tangs, seahorses among others will host and perish from Brooklynella if not treated in a timely manner. A friend in the hobby asked me recently why there isn't more written on this parasite in the scientific literature. There has been scarce little more than the original description of the new genus and species by Lom and Nigrelli back in 1970. Part of (my or the) explanation for such a dearth of investigation is the lack of food-fish importance of the principal group of fishes (clowns) afflicted. The hobby side is likely explained by an a condition of "live and let die" with so many aquarists entering and quickly exiting the marine hobby there is likely just new customers w/ no input from the old coming and going.
All new fishes should be quarantined, isolated in a separate system for a good two weeks before exposing them to established systems. As regards wild-collected Clownfishes and Seahorses this is a particular concern. In almost all cases a preventative pH-adjusted freshwater baths (Fenner 1989, 97, 98) in process of acclimation and placing of new fishes in quarantine eliminates this and other external parasitic problems. If Brooklynella expresses itself on your fishes in quarantine or a main-display setting it is necessary to act quickly to effect a cure by chemical treatment. As mentioned earlier, copper is largely ineffective in treating for this protozoan. The most efficacious cure is made by using formalin solution in either dips/baths (in freshwater or marine) or more dangerously, in administering the formalin to a system (with no invertebrates, algae, live rock present). Stock solutions of formalin (formaldehyde) are generally about 37% composition, and can be used as dips/baths of one cc. per gallon. Baths should extend for a minimum of fifteen minutes, perhaps as long as thirty... with you present (lest the animal/s need to be removed due to stress) and mechanical aeration (bubblers, airstones) added to the bath.
Yes, some Clownfishes are still wild-collected, and need be... for broodstock and for advanced aquatics studies for species not under culture. But the vast majority of keepers of these fishes will be night and day more successful trying captive-produced stock. Nowadays the dollar cost of wild versus human-made is about on par... but there the differences starkly begin. Avoid biological diseases like Brooklynellosis entirely by buying tank-bred stock. If you find yourself electing or needing to process wild-collected Clownfishes, do your best to eliminate their parasite fauna through freshwater dips, quarantine and if necessary chemical treatment.
Related WWM Articles:
Allen, Gerald R. 1980. Anemonefishes of the World: Species, Care and Breeding. Aquarium Systems, Mentor OH.
Blasiola, George C. 1980. Brooklynella, a protozoan parasite of marine fishes. FAMA 5/80.
Fenner, Bob & Steve Landino. 1989. Acclimating fishes. FAMA 8/89.
Fenner, Bob. 1997. Quarantining marine livestock. FAMA 1/97.
Fenner, Bob. 1998. A kinder, gentler dip. FAMA 2/98.
Fenner, Bob. 2000. Clownfishes. FAMA 11/00.
Lom, J. and R.F. Nigrelli. 1970. Brooklynella hostilis n.g. n. sp. , a pathogenic ciliate in marine fishes. Journal of Protozoology 17(2):224-232.
Wilkerson, Joyce D. 1998. Clownfishes. A Guide to Their Captive Care, Breeding & Natural History. Microcosm, VT.