Fish disease is an emergency for an aquarium hobbyist. If a disease is suddenly detected in your aquarium, urgent and deliberate measures taken by you will usually help avoid the worst. Many diseases, especially in their early stages, are curable. The causative agents of infectious diseases are viruses, bacteria, and fungi. Invasive diseases occur as a result of invasion—the attack on the fish’s body by animal parasites such as pathogenic infusoria, coelenterates, and worms. Some small crustaceans can also parasitize the bodies of fish. The occurrence of non-infectious diseases is in most cases associated with a violation of optimal keeping conditions in the aquarium or improper handling. As is well known, prevention is easier than cure. The most effective remedy against a possible outbreak of fish diseases in the aquarium is prevention.
• Bacteria are microscopic single-celled organisms; They are invisible to the naked eye; There are countless species of bacteria, which are divided into major categories depending on their shape; Some are genuinely beneficial to the aquarium; Pathogenic bacteria are the cause of particularly dangerous epizootics affecting aquarium fish; Substrate and water, in which certain pathogenic microbes can not only survive but also multiply, become reservoirs of infection; Antibiotics should be used only in extreme cases, when the disease is clearly manifested.
Furunculosis, Aeromoniasis, Pseudomoniasis.
• Furunculosis, Ulcer Disease; • Aeromoniasis, Red-Sore Disease; • Pseudomoniasis, White-skin disease.
• Lepidortosis, Infectious scale protrusion; • Fin rot; • Bacterial gill disease.
• Columnaris disease.
• Myxobacteriosis, Mycobacteriosis, Fish Tuberculosis.
False neon disease, Dropsy, Vibriosis.
• False neon disease; • Ascites, Dropsy; • Vibriosis.
• Viruses and viral diseases; Viruses are tiny pathogens that can only be seen with a powerful electron microscope. Viruses are intracellular pathogens, meaning they invade the living cells of their host in order to multiply.
• Lymphocystis, Cauliflower disease; • Carp pox (herpes virus); • Papillomas.
• Protozoan diseases caused by parasitic protozoa; The parasite swims actively in the water and, having found a fish, attaches to its surface with a pointed end, after which it penetrates under the epithelium of the skin, fins, gill apparatus, and oral mucosa; They can infect many species of fish and feed on their host’s skin;
• Costiosis, Costia disease, Ichthyobodo infection.
• Oodinosis, Oodinium disease, Gold dust, Velvet disease.
• Hexamitiasis, Octomitiasis, Hole-in-the-head disease.
• Cryptobiosis.
• This group of diseases is caused by various parasitic protozoa, infusoria, fluke worms, and parasitic crustaceans. These organisms have a multi-stage life cycle that includes both parasitic and free-living forms; They settle on the surface of the fish’s body, on the gills, and some parasitize inside the fish’s body.
• Chilodonelliasis; • Epistylis.
• Ichthyophthiriasis, Ich, White spot disease.
Apiosomiasis, Tetrahymeniasis.
• Apistomosis, Apiosomiasis; • Tetrahymeniasis, Guppy Disease.
• Trichodiniasis.
• These are protozoan intracellular endoparasites, myxosporidians; They settle in the fish’s musculature; When they enter internal organs, they cause blood-filled ulcers that break through to the outside; Often their clusters resemble a tumor.
• Pleistophorosis, Neon tetra disease.
• Glugeosis. • Nodular disease.
• Crustacean parasites sometimes live on the host in small numbers. The presence of any of these parasites in a home aquarium is most likely due to the use of live foods or decorative items collected in the wild; The disease is rare in the aquarium, mostly occurring in hot weather. 
• Lernaeosis (Anchor Worm).
• Argulosis, Fish louse; • Ergasilosis.
• Invasive diseases occur as a result of invasion—the attack on the fish’s body by animal parasites such as pathogenic infusoria, coelenterates, and worms; Helminthiases are diseases caused by parasitic worms; Fish helminthiases are divided into two categories: geohelminthiases and biohelminthiases. The former include helminthiases whose causative agents have a direct development cycle without an intermediate host, while the latter have one or two intermediate hosts in their development cycle.
Gyrodactylosis, Dactylogyrosis.
• Gyrodactylosis, Gyrodactylus; • Dactylogyrosis, Dactylogyrus.
Diplostomiasis, Postodiplostomiasis.
• Digenea, Digenetic trematodes; • Diplostomiasis; • Postodiplostomiasis, Black-spot disease.
• Sanguinicoliasis.
• Cestoda, Tapeworms, Cestodes; • Caryophylliasis.
• Philometrosis, Philometroidosis; • Camallanosis (camallanus worms).
• Fungi are living organisms that combine characteristics of both plants and animals and have a higher organization than bacteria. Fungal infections are among the most common diseases of aquarium fish caused by pathogenic organisms; They attack fish only if there is already tissue damage, but they can also result from other diseases.
• Saprolegniasis, Saprolegnia, Dermatomycosis (Fungus).
• Ichthyosporidiosis, Ichthyophoniasis.
• Branchiomycosis, Gill Rot Disease.
