Retrospective Review of Copper Sulfate Immersion Treatment of Marine Teleosts During Quarantine at the National Aquarium From 2004–2016
Copper sulfate immersion is commonly used during quarantine of marine teleosts for prevention and treatment of Cryptocaryon irritans.3 While an effective treatment, it has a narrow therapeutic index.1,2,4 Syngnathids are known to be sensitive to copper, but limited published information exists for other marine teleosts.2,3 The National Aquarium has routinely used copper sulfate immersion treatment during quarantine of most marine teleosts. A copper sulfate pentahydrate drip is used to increase copper concentration over 3–5 days to 0.18–0.20 mg/L [Cu2+]. This level is maintained for 21 days then the copper is rapidly removed. The methodology has been consistent since 2004. Quarantine records from 2004–2016 were used to examine mortality of marine teleosts during copper treatment. The case definition for inclusion was marine teleosts (salinity >25 g/L) that received copper treatment during quarantine.
Between 2004–2016, a total of 4,822 individual marine teleosts belonging to 338 different species received copper sulfate immersion treatment in 225 groups (1–161 per group). The first 5±1 days of treatment were at sub-therapeutic levels of <0.18 mg/L and the mean duration of copper therapy at 0.18–0.20 mg/L was 19±4 days. The total mortality during copper treatment was 4.1% (199/4,822). Of those mortalities, 27.1% (54/199) occurred during the initial increase to therapy. Copper treatment was ended early in 0.2% (12/4,822) of teleosts. Of the 338 species, 73.4% (248/338) showed no mortalities during copper treatment.
Mortality was evaluated for species with a total sample size greater than 50 individuals across more than one quarantine group. Of these larger groups, the following species experienced a total mortality over 5%: creole wrasse (Chromis retrofasciata); blue-green chromis (Chromis viridis); high hat (Equetus acuminatus); and small-mouth grunt (Clepticus parrae). Of these larger groups, the following species experienced no mortalities during copper treatment: brown chromis (Chromis multilineata); purple reef fish (Chromis scotti); porkfish (Anisotremus virginicus); feather blenny (Hypsoblennius hentzi); tomtate grunt (Halichoeres garnoti); French grunt (Haemulon aurolineatum); masked goby (Coryphopterus personatus); and yellow-head wrasse (Halichoeres garnoti).
Mortality varied by species. However, this does not necessarily represent direct copper toxicity; other stressors or disease factors may have contributed. The proportion of mortalities that occurred during the initial increase in copper concentration was greater than expected. Increased monitoring during this period is recommended, and slower increases in copper concentration may be indicated. Further analysis of other factors, such as system volume, water temperature, known parasites, concurrent medications, and water quality, is on-going.
* Presenting author
+ Student presenter
References
1. Stoskopf MK. 1993. Fish Medicine. Philadelphia, PA: WB Saunders Co; p 661–664.
2. Harms CA. 1996. Treatments for parasitic diseases of aquarium and ornamental fish. Seminars in Avian and Exotic Pet Medicine. 5:54–63.
3. Hadfield CA, Clayton LA. 2011. Fish quarantine: current practices in public zoos and aquaria. Journal of Zoo and Wildlife Medicine. 42:641–650.
4. Park K, Heo GJ. 2009. Acute and subacute toxicity of copper sulfate pentahydrate (CuSO45·H2O) in the guppy (Poecilia reticulata). Journal of Veterinary Medical Sciences. 71:333–336.