Ichthyosporidiosis, Ichthyophoniasis.
A contagious disease. In freshwater fishes, it is recorded very rarely and more commonly affects marine fishes. One of the most common and dangerous mycotic diseases. The causative agents are Ichthyophonus, Ichthyosporidium hoferi, Aphanomyces from the group of Phycomycetes, fungi, systemic mycoses. The disease develops slowly. Mass mortality of fishes is rarely observed.
Aquarium fishes of all age groups are susceptible to ichthyosporidiosis. The parasite is found in all organs and tissues of fishes, except for the skin, cartilage, and bone tissues. It is enclosed in a cyst within the affected organ of the fish. Daughter parasites are formed inside the cyst, escaping through it into the surrounding tissue. The source of infection includes fishes sick with ichthyosporidiosis, carcasses of dead fishes, infected water containing fungal spores, and food of marine origin (plankton, fish, crustaceans).
Infection occurs when a fish swallows spores entering the water from the intestines of a sick fish. After a spore or cyst penetrates the fish’s stomach, the process of fungal reproduction begins. After a few days under favorable temperature conditions, plasmodia localize in various internal organs of the host, where they become surrounded by a membrane and transform into adult forms. Subsequently, the spores are excreted through the intestines into the external environment and swallowed by new hosts.
The main harm that the parasite causes to the fish’s body lies in the formation of tumors, as well as in regressive (backward in their development) processes in individual organs, as a result of which the latter cease to function normally. Dead and decomposing fishes pose a particular danger. In this case, a reservoir of infection is formed in the aquarium. Healthy fishes should not be allowed to eat a dead fish containing parasites. Clinical signs of ichthyosporidiosis are very similar or completely coincide with those of a number of other diseases (Branchiomycosis, Dactylogyrosis, Sanguinicolosis, Fish tuberculosis, Infectious scale protrusion).
Symptoms: •— External signs of the disease may be absent for a long time or weakly expressed. Symptoms are very diverse and depend on the nature and degree of damage to a particular organ or system as a whole. Thus, with intensive damage to the nervous system, fishes show characteristic symptoms of movement coordination disorders — the sick fish loses the ability to move normally, moves uncertainly, sluggishly, and erratically, and makes convulsive swaying movements with its whole body. With severe damage to the tissues of the gill apparatus, the fish remains outwardly completely normal, but dies of asphyxiation. The presence of a large amount of fungus in the kidneys and liver leads to exophthalmia (pop-eye) and their destruction, as well as scale protrusion.
When the swim bladder is affected, the hydrostatic equilibrium of the fish is disturbed, and the fish is unable to move in the water column — they sink to the bottom and lie for a long time, adopting a lateral position. Parasitism of the fungus in the muscles and subcutaneous layer causes general weakening of the fish and the subsequent formation of surface ulcers on individual parts of the body, on which saprophytic bacteria and fungi settle, exacerbating the disease process. When ulcers develop at the bases of the fins, especially the caudal fin, complete or partial destruction of the latter occurs. Only the fin rays remain from the affected fins.
Regardless of the clinical manifestation, the sick fish refuses food, loses weight, and its resistance to causative agents of invasive diseases and unfavorable environmental conditions decreases. Since ichthyosporidiosis usually proceeds chronically and for a long time (more than a year), fish mortality is not of a mass character; only those individuals in which the pathological process has reached a certain critical form constantly die. In some cases, symptoms are completely absent, and the diagnosis is established after necropsy.
Treatment: Effective therapeutic agents for combating ichthyosporidiosis have not been found to date. Treatment mainly boils down to prevention. Sick and suspected fishes are destroyed. Optimal maintenance and feeding conditions are created in aquariums, overcrowding is avoided, and cleanliness is maintained. Newly acquired fishes are subjected to quarantine for a month. Water vegetation is disinfected with bicillin-5 solutions. Fishes are destroyed, and the aquarium is disinfected.
Causative agents can be contained in food of marine origin (plankton, fish, crustaceans). According to some reports, results in the early stages of the disease have been obtained using the fungicides phenoxyethanol and parachlorophenoxyethanol. Phenoxyethanol is diluted in water in a 1:100 ratio and poured into the aquarium at the rate of 10-20 cm³ of such solution per 1 liter of aquarium water. At the same time, dry food is soaked in the same solution before feeding the fishes. After treatment, the water in the aquarium is changed. Parachlorophenoxyethanol is diluted in water in a 1:1000 ratio and gradually added to the aquarium over two days at the rate of 50 ml of such solution per 1 liter of aquarium water, after which the water in the aquarium is replaced with fresh water. Ultraviolet (UV) irradiation helps for prevention.
Medicines: Aquarium Pharmaceuticals Aquarium Salt; Aquarium Pharmaceuticals Fungus Cure Powder; Aquarium Pharmaceuticals Furan-2; Aquarium Pharmaceuticals Liquid Fungus Cure; Aquarium Pharmaceuticals MelaFix; Aquarium Pharmaceuticals Triple Sulfa; Aquarium Pharmaceuticals E.M. Tablets; Aquarium Pharmaceuticals T.C. Capsules; Sera ectopur; Sera mycopur; Sera Omnipur; Sera omnisan; Tetra ContraIck plus; Tetra Fungi Stop; Tetra General Tonic; Tropical Akriflawina; Tropical Akryflawina; Tropical Aquaseptin; Tropical Biodesinal Pond; Tropical Ichtiosan Pond; Tropical MFC-2000; Akrimet; Antipara; Gentian violet; Griseofulvin; Collargol; Merbromin (Mercurochrome); Methylene blue; Nystatin; Rivanol; Sodium chloride (sea salt), table salt; Copper sulfate; Phenoxyethanol; Phenoxyethanol; Fiosept; Some bactericidal agents are simultaneously fungicidal (antifungal).
