There is literature showing the killing effects of H2O2 on the malaria parasite and gram-negative bacteria and the application in aquaculture.
Article abstract in the Journal of Aquatic Animal Health 2000:12(4):
The efficacy of hydrogen peroxide to control external parasitic infestations on juvenile (10–33-g) rainbow trout Oncorhynchus mykiss was evaluated in three clinical field trials. Fish were exposed to hydrogen peroxide concentrations ranging from 0 to 560 mg/L for 30 min once every other day for a total of three treatments. Pre- and posttreatment skin scrapes and gill wet mounts of test fish were microscopically examined to identify and enumerate external parasites. Infestation severity was classified as nonexistent (0 organisms), low (1–10 organisms), moderate (11–20 organisms), or high (21 organisms). In trial 1, pretreatment skin examinations revealed a severe infestation of the protozoan Ambiphrya on all fish examined. Posttreatment skin examinations conducted within 24 h of the last treatment indicated that all hydrogen peroxide treatments eliminated Ambiphrya, whereas control fish remained severely infested with the protozoan. In trial 2, pretreatment examinations of skin and gill samples indicated a high infestation of the trematode Gyrodactylus (skin) and the protozoan Trichodina (gills) on all fish. Posttreatment examinations conducted within 24 h of the last treatment indicated that Gyrodactylus was eliminated from the skin of all treated fish; however, the high infestation of Trichodina remained on the gills of the test fish. All control fish had high infestation levels of both parasites. A high infestation of Ambiphrya was found on the skin of test fish before treatment (trial 3). Posttreatment examinations conducted 14 d after the last treatment revealed that 56% of the fish were parasite free, whereas the remaining test fish had low infestation levels. Control fish remained severely infested with the parasite. Based on the efficacy data, all hydrogen peroxide treatment regimens were efficacious in the control of Ambiphrya and Gyrodactylus.
Article abstract in the Journal of Aquatic Animal Health 2007 19(2):
The objectives of these preliminary studies were to evaluate the use of hydrogen peroxide (H2O2) for the treatment of selected species of ornamental fishes and its efficacy in treating external bacteria and parasites. In the first part of the study, fish of five species (serpae tetra Hyphessobrycon eques (also known as Serpa tetra H. serpae), tiger barb Puntius tetrazona, blue gourami Trichogaster trichopterus, suckermouth catfish Hypostomus plecostomus, and green swordtail Xiphophorus hellerii) were exposed to H2O2 for 1 h at concentrations between 6 and 34 mg/L or for 24 h at concentrations between 1 and 6 mg/L. The results were species specific: green swordtails tolerated all of the treatments, serpae tetras and tiger barbs were sensitive only to the highest concentration, and mortalities of suckermouth catfish and blue gourami were recorded in every treatment. In the second part of the study, clinically healthy green swordtails and fish infested with external motile rod-shaped bacteria (i.e., Ichthyobodo spp., Trichodina spp., and Gyrodactylus spp.) were treated with several concentrations of H2O2. A single H2O2 treatment of 3.1 mg/L or more for 1 h effectively eliminated external bacteria, concentrations of 6.5 mg/L or more appeared to effectively kill Ichthyobodo spp., and none of the treatments tested was effective against Trichodina spp. or Gyrodactylus spp. These preliminary findings suggest that H2O2 is effective for treating certain external bacterial infections and flagellate infestations in some species of ornamental fish at the dosages tested. Other treatment regimens may need to be tested for effectiveness against Trichodina spp. and Dactylogyrus spp.
North American Journal of Aquaculture 2013 75(1):
Burbot Lota lota is an emerging aquaculture species, in which fungal infestations during early life stage development are common. In this study, the tolerance of Burbot to external hydrogen peroxide (H2O2) treatment regimes was examined during four early life stages to determine species and life stage-specific sensitivity. Yolk-sac larvae tolerated three 1-h treatments up to 250 μL/L H2O2 without significant reduction in survival. Preflexion larvae tolerated only 100 μL/L H2O2 before survival was affected. In both cases, decreased survival was only observed after administration of three consecutive treatments. Flexion larvae tolerated up to 250 μL/L H2O2, but by the juvenile stage sensitivity again increased to 100 μL/L H2O2 before survival was affected. In these latter stages, decreased survival was observed immediately following the first H2O2 treatment, suggesting a mechanism for toxicity that is different than that in previous life stages. As has previously been shown, H2O2 can be effective for controlling aquatic bacteria and fungus at or below 250 μL/L, and our results indicate that H2O2 concentrations currently used during Burbot egg incubation may be extended into the larval rearing stage for effective fungal control without negatively affecting survival of either eggs or newly hatched larvae. Additionally, treatment regimes may be continued through juvenile development for the purpose of controlling external pathogens in the hatchery production of Burbot.
North American Journal of Aquaculture 2012 74(1):
The aim of the present work was to simulate water treatment practices with hydrogen peroxide (HP) in recirculating aquaculture systems (RAS). Six identical 1,700-L pilot-scale RAS were divided into two experimental groups based on daily feed allocation and operated under constant conditions for a period of 3 months. The organic and nitrogenous loadings of the systems differed fourfold between the two groups and were achieved by predefined constant daily feed loads and constant additions of water. The fixed cumulative feed burden was 1.6 × 103 mg feed/L in the low-intensity RAS and 6.3 × 103 mg/L in the high-intensity RAS. The decay of HP in rearing tanks and disconnected biofilter units was investigated by means of HP spiking experiments. The decay in high-intensity RAS rearing units and biofilters was orders of magnitude faster than that in low-intensity units. The application of HP impaired biofilter nitrite oxidation in low-intensity RAS but not in high-intensity RAS. The impact of HP exposure time on biofilter nitrification capacity was then assessed in biofilter bench-scale experiments with nitrite spiking. Exposure time was found to significantly affect nitrite oxidation. Compared with unexposed biofilter elements, nitrite oxidation was reduced more than 90% following 3 h of exposure to 15 mg HP/L, whereas 30 min of exposure had only minor negative effects on nitrite oxidation. The findings of this study demonstrate the potential for developing HP water treatment practices for RAS and contradict prevailing notions that HP cannot be used safely in RAS that employ biofiltration. The development of effective new HP treatment protocols for recirculating aquaculture could reduce the current dependence on formalin to improve water quality and control parasitic loads.
The Progressive Fish Culturist 1994 56(4):
The antifungal activities of 21 chemicals against species of Saprolegnia, a ubiquitous genus of aquatic fungi frequently found in fish hatcheries, were evaluated with pure fungal culture and with Saprolegnia-infected eggs of rainbow trout (Oncorhynchus mykiss). Fourteen compounds were ineffective for control of fungus on rainbow trout eggs or were toxic to the eggs. The seven compounds that effectively controlled fungus on infected eggs and provided a reasonable margin of safety were Abbott A-73336, amorolfine, formalin, glutaraldehyde, hydrogen peroxide, melaleuca, and salt (sodium chloride). Only formalin, hydrogen peroxide, and salt appeared completely suitable for registration. Formalin, the replacement antifungal agent, is restricted to use with the eggs of salmonids and esocids. User safety and the effect of effluents on the environment are also concerns related to formalin treatments. Formalin effectively prevented fungal infections on eggs at concentrations as low as 250 ppm. A 1,000-ppm treatment of formalin not only prevented infection but also decreased existing infection and increased hatching rates at exposures of 15, 30, or 60 min. Hydrogen peroxide at concentrations of 500 and 1,000 ppm controlled fungus on infected eggs and increased hatching rates of treated eggs. Hydrogen peroxide was recently classified by the U.S. Food and Drug Administration as a low regulatory compound when used to control fungi on all species and life stages of fish, including eggs, and it is the antifungal agent of choice for further development. Salt decreased infection level and increased hatching rate of infected eggs at a concentration of 30,000 ppm. Salt is readily available and listed as a low regulatory compound, but the large quantities required limit its applicability.
