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Appl Environ Microbiol. 1991 June; 57(6): 1813–1816.
PMCID: PMC183473

Effect of sublethal concentrations of four chemicals on susceptibility of juvenile rainbow trout (Oncorhynchus mykiss) to saprolegniosis.


The effects of sublethal concentrations of a variety of chemicals on the susceptibility of rainbow trout (Oncorhynchus mykiss) juveniles to Saprolegnia parasitica infection was examined. Sublethal concentrations of un-ionized ammonia (0.05 mg/liter) and nitrite (0.12 mg/liter) increased fish susceptibility after 10 days of exposure to the toxin, this increase being higher for ammonia (75% and 20% morbidity) than for nitrite (20% and 0% morbidity, respectively) with inoculum doses of 1.4 x 10(6) and 9.5 x 10(5) zoospores per liter, respectively. Sublethal concentrations of copper (0.05 mg/liter) or cyanide (0.05 mg/liter) did not show enhancement of infection by S. parasitica, even though the toxin exposure was for 21 days and the inoculum doses were higher than those for the experiments with the nitrogen compounds (4 x 10(6) and 3.2 x 10(6) zoospores per liter. However, infections began to appear in control animals.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Dixon DG, Leduc G. Chronic cyanide poisoning of rainbow trout and its effects on growth, respiration, and liver histopathology. Arch Environ Contam Toxicol. 1981;10(1):117–131. [PubMed]
  • Ewing MS, Ewing SA, Zimmer MA. Sublethal copper stress and susceptibility of channel catfish to experimental infections with Ichthyophthirius multifiliis. Bull Environ Contam Toxicol. 1982 Jun;28(6):674–681. [PubMed]
  • Hetrick FM, Knittel MD, Fryer JL. Increased susceptibility of rainbow trout to infectious hematopoietic necrosis virus after exposure to copper. Appl Environ Microbiol. 1979 Feb;37(2):198–201. [PMC free article] [PubMed]
  • Nolard-Tintigner N. Etude expérimentale sur l'épidémiologie et la pathogénie de la saprolégniose chez Lebistes reticulatus Peters et Xiphophorus helleri Heckel. Acta Zool Pathol Antverp. 1973 Mar;57:1–127. [PubMed]
  • Pickering AD. Cortisol-induced lymphocytopenia in brown trout, Salmo trutta L. Gen Comp Endocrinol. 1984 Feb;53(2):252–259. [PubMed]

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