International Giant Otter Studbook Husbandry and Management

Nutrient values vary between fish species and even within the same species depending on age,
sex and season of capture (Crissey 1998). Merck (1986) states “Many fresh-water and saltwater
fishes contain thiaminase, an enzyme that results in thiamine [vitamin B 1 ] deficiency in
animals fed exclusively on a diet of such fish.” Lewis (1995) states, with regards to mustelids,
“Diets high in polyunsaturated fat or fish may predispose vitamin E deficiency.” The process of
fish storage (freezing), thawing, and preparation causes fish nutrient loss, particularly vitamins
B 1 and E, and especially in fish with a high fat and/or high thiaminase content (Crissey 1998,
Merck 1986). Fish types containing high thiaminase and/or high polyunsaturated fat levels
should be avoided, as they can cause malnutrition, sickness and even death (Merck 1986).
Vitamin supplements, most especially vitamin B 1 (thiamine), vitamin E, and a
multivitamin, must be added when thawed frozen fish is the main diet. Vitamins should be
fed separately from the main feedings by at least 2 hours, so proper vitamin utilization can
occur, esp. vitamin B 1 (Merck 1986). Vitamins can be offered in the gills or throat of fish low
in thiaminase (Merck 1986). (See under “Dietary Related Problems” in Chapter 1 Section 4A
for more information on vitamin B1 and E deficiencies and the related health
problems/symptoms.) Hagenbeck Tierpark (Hagenbeck & Wünnemann 1992) increases
vitamin supplements during pregnancy and lactation and increases calcium during lactation.
Lactating and pregnant otters will generally need an increased diet. Lactating giant otters have
increased food intake from 2-3 kg/day to 6 kg/day (Hagenbeck & Wünnemann 1992).
Complete dietary guidelines for the giant otter need to be developed. No conclusions have
been drawn on the appropriateness or nutritional value of the foods or supplements
offered at the 16 zoos that responded to the survey. The examples following are to serve
only as an overview and not recommendations. Due to space limitations, only one
institution’s vitamin regimen and some (mostly) principal diets will be given as examples. All
institutions offer fish daily (thawed frozen fish, live fish, and/or freshly caught fish), as the main
diet. (Four zoos did not specify fish type fed.)
Chestnut Centre feeds live fresh water rainbow trout (Salmo gairdneri) as the principal diet.
Duisburg Zoo feeds live fresh water rainbow trout almost daily and every second day freshly
killed carp (Cyprinus carpio) is fed in addition. Cali Zoo feeds river fish (species not identified)
and live Tilapia, and Brasilia Zoo feeds Tilapia as the main diet. Hagenbeck Tierpark fed
thawed frozen redeye (Rutilus rutilis) and common bream/brachsen (Abramis brama) for the
principal diet, and herring (Clupea harengus), mackerel (Scomber scombrus) and live water
rainbow trout for variety. Dortmund Zoo feeds live rainbow trout, thawed frozen felchen
(Coregonus albula), redeye and common bream/brachsen as the principal fish. Herring and
mackerel are fed to administer vitamins and small amounts are fed during husbandry training
sessions. Philadelphia Zoo gives one 100 mg vitamin B 1 tablet and one 400 IU vitamin E geltab
per otter daily, and in addition 1 tablet of K-dec (multiple vitamin & mineral for adult humans)
3 times/week per adult otter. Thawed frozen freshwater rainbow trout, their main diet, is fed 7
days/week. Fresh water channel catfish (Ictalurus punctatus), herring and mackerel are offered
occasionally for variety. Madrid Zoo (Spain) fed freshwater trout as the main diet and marine
fish to supplement. Emperor Valley Zoo (Trinidad) offers Tilapia mosambica, Chicliasoma
bimaculatum, Tarpon atlanticus, and Priacanthuus cruonthalus (etc.) as a principal diet. The
Aquatic Mammal Research Center (Brazil) feeds Sardinha, Tucunare, Curimata [? Curimbata
(Prochilodus lineatus) ?], Jappqui, Pipanha, Pacu, Mapapa, and Capa (Portuguese common
names).
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