Its natural for fish to carry a small population of microscopic skin and gall parasites. In healthy fish, this population is kept in check. But when fish are stressed, this population rapidly increases and endangers the fish's life. Often this causes the fish to increase its mucus production, resulting in the so-called "slime symptom". Anti Parasite, Slime and Velvet eradicates velvet, flukes and protozoan parasites from your aquarium, helping your fish to regain a healthy balance and return to health. Use for removing parasites from your aquarium such as microscopic protozoan parasites (Costia/Ichthyobodo), Trichodina, flukes (Gyrodactylus) and Velvet (Piscinoodinium). Do not use with scaleless fish or invertebrate