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Longevity of Marine Tropicals at The Nancy Aquarium

By B. Conde, Nancy, France

(Reprinted from Revue Francaise d'Aquariologie: 9 (1982), 4 March 1, 1983. The fishes marked with a (*) in the table were still on display in May, 1986)

One will find excellent longevity of marine tropicals here. With few exceptions, longevity is greater than 5 years.

The tropical tanks at the Nancy Aquarium are all automated. They work on a semi-closed system with the addition of new synthetic seawater by means of a drip system, regulated by the level of nitrates in the water, which are not permitted to exceed 20 milligrams per liter NO₃-N. Filtration is by means of polyester foam, and the water circulates through an ultraviolet lamp after passing through the filter.

Particular attention is given to stocking the tanks, a good equilibrium between the inhabitants appearing to be a condition affecting the longevity of the inhabitants and their resistance to parasites. The quarantine procedures, the first phase of a successful acclimation, are given a great deal of attention. Nets are used on the fish only when capture proves to be impossible with traps or other vessels; if a net must be used, the fish is released underwater in the transport.

The first tropical marine fishes came to Nancy on October 21, 1967. The longest-surviving fish are Dascyllus cameus (10/21/67); Forcipiger flavissimus and Rhinecanthus rectangulus (6/14/68); Arusetta asfur, Zebrasoma desjarinii, Abudefduf sexfasciatus, and Dascyllus marginatus (6/20/69): Amphiprion ocellaris, A. clarkii, and A. frenatus (6/27/69); Platax teira and Balistapus undulatus (7/15/69); and Naso annulatus (10/24/69). The last three species were in homes for a year before being offered to the aquarium by their owners. The longevities represented by 8 families are the subject of the following tables:

The Pygoliptes diacanthus, Arusetta asfur, Euxiphipops navarchus, and Chaetodontoplus mesoleucus have shown modest body growth (2-3cm)

The two Euxiphipops xanthometapon were brought together in a tank on 3/9/82. The first occupant, which was rather large, showed interest in the new arrival with a dominance display followed by some pursuit but no serious battles. The two specimens were then found from time to time displaying to each other with flared fins. The two Apolemichthys xanthurus which share the some tank and were reared together since their acquisition (about 30 mm) show similar behaviour to that of the Euxiphipops. After its introduction, the second E. xanthometapon was the subject of a sharp attack from Pomacanthops semicirculatus.

Forcipiger longirostris was only at Nancy for 2 years and 9 months, but it did not appear to be any more demanding in its care than F. flavissimus.

The maximum longevity of a representative genus Chaetodon is 14 1/2 years for a C. rafflesi. C. semilavartus survived nearly 13 years and died accidently when polluted fresh water was accidently poured into its tank.

In the case of C. meyeri and C. ornatissimus, the closely related species (apparently hybrids from Palau) generally accept ground mussels. They have a more or less prolonged juvenile stage which is particularly dangerous to small specimens. Those of meyerii (50mm total length) did not survive more than 56 days, but a large individual of the same species (100mm total length) lived a little more than 6 months (9/1/76-3/12/77). On 9/18/79, a juvenile C. meyeri (60mm), received from Mombasa, was introduced into a tank containing various kinds of Madreporarians (stony corals), among which were Goniopora sp. (brain corals), Plyogyra sinuosa (bubble coral), P. sinuosa var. cultifera (bubble coral), and Trachyphyllia geoffroyi. The fish immediately began to browse on the Trachyphyllia, which was eaten in several days. This food was renewed and was consumed equally (after about 3 weeks) with the chopped mussels. The animal also browsed on a wall of small anemones and later attacked some Plerogyra sinuosa cultifera which was totally destroyed, whereas the P. sinuosa types were not touched. J.P. Chevalier wrote on this subject: "It is rather curious that the Chaetodon, more gifted in classification than the zoologists, is better able to distinguish between P. sinuosa and P. cultifera than anyone since Matthai (1928), and classifies them in the same way. The latter species differs from the first only in that the radial elements were more pronounced. Personally, I also place cultifera with sinuosa. Perhaps there are other physiological criteria more trustworthy." Between times, raw mussel was taken (at least one per day), although its attractiveness was lessened by cooking, and it made up the bulk of the food.

Our two Acanthurus leucosternon, which lived for 11 years and 3 months and 10 years and 11 months, respectively, showed towards the end a loss of weight and violent attacks of cutaneous parasites, responding little or not at all to the usual treatments. Moreover, one of them ingested quantities of quartzite before dying.

One ctenochaetus hawaiiensis, acquired just as it was changing from the juevnile coloration (chevron tang) to the adult pattern (the chevrons resolve into fine longitudinal lines of metalli blue-green), died after 10 years 2 months (7/1/72-8/28/82). Its sudden death, in the night, was not preceeded by any symptoms and it is possible that it was a victim of trauma.

B. undulatus was offered to us by an amateur after about 1 year in an aquarium.

The greatest longevity was with Arothron hispidus, acquired 7/18/68 and died 5/27/81 after becoming progressively weaker. As it was a specimen living in an aquarium almost two years before its acquisition, at the date of its death one can estimate the duration of its captive life at fifteen years. One arothron died of an occlusion after 8 years at the aquarium.

The Chilomycterus orbicularis still living is the male of a pair of which the female, acquired at the same time, spawned several times. Her last spawn, June 26, 1980, at 5:00 PM., gave birth to a number of fry which survived a month on the nauplia of Artemia, before becoming victims of a rise in the nitrate level in the tank. The female died 10/13/80, in a weakened condition with a distended abdomen from the last spawn.

Aquatic Interiors, Seacave