Bony fishes: filling welfare evidence gaps in aquariums

Bony fishes can receive careful daily husbandry while remaining poorly represented in published behavioural research. The two observations answer different questions. A gap in the literature does not rank aquariums by their standard of care, and it cannot establish how the animals in a particular exhibit are experiencing their environment.

Oldfield and Bonano addressed the publication gap in a paper appearing in the 2023 volume of Zoo Biology, following online publication in 2022. Their analysis provides a starting point for examining the evidence available to an aquarium team. It can also help identify questions worth documenting within a collection, rather than waiting for one assessment tool to cover every species.

Publications were the unit of enquiry

The authors surveyed research articles and reviews in three zoo-oriented journals from January 2007 to January 2019. Two journals concerned with behaviour and conservation provided comparisons. Bony fishes were considered separately from sharks and rays, which earlier surveys had often combined within a general fish category.

Representation was assessed against species richness. That denominator is different from the number of captive individuals or the hours staff spend caring for them. The selected corpus excluded a veterinary journal focused on health and an informal aquarium publication. It was therefore not an exhaustive inventory of all evidence relevant to collections.

Bony fishes were underrepresented in the zoo-oriented journals examined. The finding concerns those publications and that historical period. It should not be presented as a complete audit of evidence available in 2026, still less as evidence that every aquarium lacks knowledge about its fish.

Map the evidence against the collection

One practical response is to compare the team’s reference library with its species list. Which teleosts have relevant behavioural studies? Do those studies address the same species, a comparable life stage and a reasonably similar setting? A long bibliography may depend heavily on a few familiar research models.

This local evidence map is an editorial suggestion for using the finding, rather than a validated protocol produced by the literature survey. It can show where staff rely on published aquarium studies, general recommendations, keeper experience or extrapolation from farming and biomedical research. Each can contribute, provided its role and limits are clear.

A species with little published evidence still needs attention. The useful next step is to describe an uncertainty and turn it into an observable question. Starting with a specific problem also makes collaboration between keepers, biologists and veterinarians more productive than attempting to measure every possible aspect of behaviour at once.

Choose the question before the measure

Smith’s review of welfare in public aquariums discusses the need to consider animals together with their living conditions. A local question might concern access to food, social interactions or use of a shelter. The appropriate priority depends on the group’s history and the difficulties staff have actually observed.

An ethogram defines the behaviours and the rules for recording them. This helps prevent one observer labelling a movement exploration while another calls it agitation. Definitions can include when an animal is out of view, since failure to see a fish is not equivalent to observing it inactive.

The sampling plan then specifies animals or zones, timing, session length and relevant events. These choices shape the comparison that can be made. A different camera angle or observer may change detectability even when the fish behave in the same way. Method changes belong in the record alongside changes in husbandry.

A single sign cannot carry the welfare conclusion

Behavioural measures should be considered alongside injuries, body condition, feeding and water conditions. More swimming may reflect exploration or disturbance, depending on context. Aggregation likewise has several possible social and environmental explanations. Interpretation requires more than assuming that increased activity is beneficial.

Observations that challenge the initial hypothesis should be retained. Following a change in food presentation, greater activity with unequal access to resources would demand a different response from an increase shared across the group without observed conflict. This is an example of possible reasoning, not a result reported by the cited studies.

Environmental enrichment therefore needs more than confirmation that an object was installed or that visitors found it attractive. A clear question, comparable observations and a search for unwanted effects make assessment more useful. Conclusions should remain attached to the animals, conditions and time window actually examined.

Keep a record another team can use

A short internal report can preserve the reason for an observation, definitions, timings, limitations and resulting decision. Another team can then see what was tried and why. This also reduces the chance of repeating an abandoned intervention after the explanation for its removal has been lost.

Publishing research requires additional work on study design and analysis. Routine observation is not automatically an experiment, and a large video archive does not provide as many independent replicates as it contains frames. Discussing the question with research partners before collecting more data can prevent an impressive dataset that cannot support the intended comparison.

Turn a gap into a manageable enquiry

The publication gap supports better questions about bony fishes without an automatic judgement on existing care. A useful first project may be modest: define one behaviour reproducibly and explain how observing it informs a real husbandry decision. Its value comes from clarity and traceability rather than the number of variables collected.

Vetofish animal welfare support can help teams select questions and observation criteria. Work with public aquarium teams connects behavioural information with clinical findings and environmental records specific to their collections.