Saprolegniasis, Saprolegnia, Dermatomycosis (Fungus).
A contagious disease. The causative agent is mold fungi of the Saprolegniales group from the genus Saprolegnia parasitica, S. mixta, S. ferax, S. monica, Achlya flagellata, Aphanomyces, Dictyuchus, Leptolegnia. It develops in fish whose organism is weakened as a result of some other disease or poor maintenance conditions. It often appears against the background of other infectious and invasive diseases as secondary infections. Mold fungi are always present in aquariums, but a significant amount of them is found in bodies of water with a high content of organic substances in the form of leftovers of uneaten food, dead mollusks, and other aquatic organisms.
A healthy and well-fed fish kept in optimal conditions never contracts Saprolegniasis, despite the presence of the pathogen in the aquarium. The disease manifests itself predominantly in those aquariums where fish are kept in cramped conditions with dirty and cold water — below 20°C.
Mold fungi are branched filaments called hyphae. With the help of thin, highly branching hyphae, the fungus invades the outer tissues of the skin and gills, sometimes penetrating into the subcutaneous tissue, muscles, and even internal organs. Hyphae extending into the environment, i.e., water, are larger and weakly branching. With severe damage, these hyphae form white or yellowish thickets, externally resembling cotton wool.
Most often, it localizes on the skin and gill apparatus of the fish in places where their integrity is violated as a result of various injuries, ulcers of infectious and mycotic origin. Dermatomycosis, being a secondary disease, significantly complicates the course of the main disease and thereby accelerates the death of the sick fish. As the infection progresses, external mycosis can grow into internal mycosis.
Symptoms: •— At the beginning of the disease, thin white hyphae of the fungus appear on individual areas of the skin, fins, and gills of fish, more often at the site of injuries, ulcers, and cuts, along with white spongy formations on the skin with long fibers extending perpendicularly from the site of localization. •— On individual areas of the skin, fins, eyes, and gills of the fish at the sites of wounds and ulcers, thin white threads initially appear, which soon form a cotton-like coating of white or light-yellow color. If during this period the aquarist does not take measures to improve the conditions of maintenance and feeding of fish or eliminate the cause of the underlying disease, the fungus will develop rapidly and will be clearly visible to the naked eye.
•— It resembles a cotton-like coating of white or light-yellow color, consisting of many intertwined hyphae. The fungal hyphae entwine the skin and gill cells, causing oxygen starvation followed by necrosis. •— Fins shorten, stick together, and disintegrate. •— The fish refuses food and becomes sluggish. It often lies on the bottom. •— Clouding of the eyes, turning into a cataract. •— Exerting a similar pathogenic effect, hyphae affect the subcutaneous tissue, muscles, and sometimes internal organs. Advanced forms of the disease, when the fungus affects the muscles and internal organs, end in the death of the fish. •— As a rule, fungi act together with other pathogens. As soon as the fish weakens or gets injured, the fungus parasitizes on it.
Treatment: If the fungus affects internal organs, the fish dies. After establishing the diagnosis, it is necessary to find the cause of the underlying disease. By eliminating the causes, improving maintenance and feeding conditions, and carrying out sanitary measures, fish recover, but weakened individuals die. Since these fungi grow only on dead material, they settle on damaged tissue. If the development of mold fungi on a fish is a consequence of any disease of infectious or invasive origin, it is necessary to start treating the main disease, treat the bacterial infection with antibiotics, after which the fungi will disappear.
In the initial stage, the disease can be stopped. White streptocide is added to the general aquarium. Baths in a separate vessel — copper sulfate, malachite green, formalin, chlorhydrate, table salt, rivanol. A 5% solution of table salt is used in a separate vessel, in which fish are kept for 5 minutes. Eliminating the disease is facilitated by increasing the water temperature and simultaneously enhancing its aeration.
If the fungus appeared after mechanical damage, it can be eliminated by placing the fish in a separate vessel with a solution of Malachite Green Oxalate. The fungi will be quickly killed, but this does not help with bacterial infection. During treatment, the temperature is raised to 26°C. Untreated fungi eventually acquire a color from gray to reddish-brown as dirt and algae accumulate in them. When treating in a separate vessel, medicinal solutions of Copper Sulfate are used at a dose of 1 g per 10 l of water with an exposure of 30 minutes (treatment is repeated every 12 hours for 10 days).
Medicines: Aquarium Pharmaceuticals Fungus Cure; Sera ectopur; Sera mycopur; Tetra General Tonic Plus; Tetra Medica Fungi Stop; Antipara with Antibak; Acrimet; Bicillin-5; Gentian violet; Malachite green; Methylene blue; Nifurpirinol; Basic Violet K; Table salt; Rivanol; Streptocide; Sulfadiazine; Copper sulfate; Sulfamethoxypyridazine; Phenoxyethanol; Formalin; Quinine;
Prevention comes down to preventing the emergence of other diseases in the aquarium by creating optimal conditions for keeping fish, their diverse and complete feeding, and maintaining a proper sanitary condition in the aquarium. Special attention should be paid to the timely removal of food residues, dead mollusks, and fish from aquariums.
