August 2026

Quick Answer Trichodina and Costia are both protozoan parasites too small to see with the naked eye, and both are confirmed the same way — a skin or gill scrape examined under a microscope. Trichodina is round, spins like a flying saucer, and is visible at 100x magnification; Costia is far smaller, comma-shaped, and needs […]

Quick Answer Koi ich (white spot disease) is caused by Ichthyophthirius multifiliis, a protozoan parasite that shows up as tiny white spots — like grains of salt — scattered across the body, fins, and gills. Unlike anchor worm or fish lice, these spots don’t move and aren’t attached structures; they’re the parasite itself embedded in