International Giant Otter Studbook Husbandry and Management

...Consumption rates of wild otters may be higher than captive otters, as wild
otters must expend more energy obtaining their food (Nolet & Kruuk, 1994).
...Captive preferences generally agree with diets of wild giant otters.
Characiformes are widely consumed by wild otters, along with Perciformes
and Siluriformes (Carter & Rosas, 1997). Captive otters readily consumed a
variety of characoids and the only siluroid offered. At a species level,
however, fish preferred by captive otters are not always consumed in the same
proportions by wild otters in the same region (central Amazonia). For
example, Anostomidae were preferred in 100% of captive trials, and Schizodon
sp. was the most common prey of giant otters in the Curua-Una hydroelectric
reservoir (Best, 1984). However, Anostomidae were only present in 16.2% of
scats from a tributary of the upper Jauaperi river (Rosas et al., in press).
Similarly, siluroids were high1y preferred in captivity, but present in on1y
5.4% of scats (Rosas et al., in press). Serrasalminae were generally not
preferred in captivity (25.0% of trials), but were relatively common in scats
(18.9%, Rosas et al., in press). Serrasalmidae were also commonly consumed
(25% of scats) by otters in the Balbina hydroe1ectric reservoir (Benetton et al.,
1990). Captive preferences and wild consumption of Myleinae were similar
(3.3% of captive trials, 5.4% of scats, Rosas et al., in press).
...In summary, captive giant otters exhibited significant preferences for
different genera and sizes of fish, and preferences varied with individual otter.
Differences between captive preferences and observed diets of wild giant otters
suggest that prey availability may be more important than preference in
determining diet composition of wild otters. Method of consumption of fish by
captive otters varied with the species and size of fish. This should be
considered when determining diet composition from scats, as hard parts,
particularly otoliths, of some species and sizes of prey may not be consumed.
Transit time is relatively short in giant otters, but same hard parts may be
retained in the digestive system for longer periods of time, introducing
potential bias to studies using frequency of occurrence to describe feeding
habits of giant otters in the wild."
Excerpts from Carter and Rosas (1997) on giant otter diets.
"...The present authors found that a captive adult consumed 10% (range 6.0-
16.0%) of its body weight daily and a subadult consumed 13.4% (range 8.0%-
18.9%). These results are similar to studies by Zeller (1960) and Best (1985)
which reported daily food consumption by adults and subadults is 7.0-9.6%
and 12.9% of their body weight, respectively. Schweizer (1992) reported a
higher consumption rate of 25% of the total body weight for one sub-adult."
"...Direct observation and faecal analysis in various regions have revealed that
fish constitute the majority of the [wild] Giant Otter's diet...Wild adults
consume an estimated 3 kg of fish daily (Duplaix, 1980; Schweizer,
1992)....Most fish consumed by [wild] Giant Otters belong to the suborders
Characoidei (characins), Percoidei (perch) and Siluroidei (catfish). Species
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