Fish treatment and quarantine: what a survey of 350 hobbyists and retailers reveals
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
Quarantining a new fish for a few weeks before introducing it is well-known advice, but what do hobbyists and retailers actually do once a fish is suspected of being sick? A survey by Arapi and Cable, of Cardiff University, published in 2025 in Academia Biology, questioned more than 350 participants in the UK about their practices facing infectious diseases in freshwater ornamental fish (see the study, doi 10.20935/AcadBiol7832). Our guidance on introducing a new fish is gathered in the travel and safety section.
Contents · 6 sections
Different habits between hobbyists and professionals
The survey's first finding: hobbyists use proportionally more products marketed as "natural", while retailers rely more on synthetic treatments, sometimes applied prophylactically to limit economic losses before any visible symptoms even appear. Both groups closely monitor water quality, but only retailers treat their fish at a set time of day, a regularity hobbyists apply far less consistently.
A recurring problem: treating without a diagnosis
The survey flags a common pitfall on both sides: starting a treatment without a confirmed diagnosis, with dosing that does not always precisely follow the manufacturer's instructions. This trial-and-error approach raises the risk of treatment failure — the wrong product against the wrong pathogen, or an insufficient dose that lets the disease return once treatment stops.
What this says about the whole chain
The authors' conclusion goes beyond any single individual's actions: relying solely on each link's own practices, from wholesaler to retailer to hobbyist, is likely insufficient to prevent pathogens from being introduced and spreading through the trade. One weak link is enough to undermine everyone else's efforts.
What this survey does not show
This is a self-reported questionnaire, not a direct observation of practices or a measurement of the treatments' clinical effectiveness: reported behaviour may differ from what is actually done. Nor does the survey quantify the exact share of diseases actually caused by these diagnostic or dosing gaps, only how often they were reported.
What this means for a buyer
This result strengthens the case for a step many hobbyists skip for lack of space: quarantine before introduction, which is precisely what limits the risk of having to treat an already-contaminated tank in an emergency, without a clear diagnosis. Before any treatment, pinning down the exact problem pays off more than trying one product after another.
Frequently asked questions
Are "natural" products less effective than synthetic treatments?
The survey does not compare their clinical effectiveness, only who uses them and under what circumstances; it cannot settle that question.
Does a reputable fish store always treat its stock preventively?
Some of the retailers surveyed do, to limit economic losses, but the survey shows this practice is not universal. Find all our guides on the fishkeeping hub.
See it in the Planète Pets shop: 6 cm nano air diffuser with suction cups for aquariums (€19.90) · the whole shop
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.