What does a fish tick look like? - briefly
A fish tick is a minute, oval-shaped ectoparasite about 1–3 mm long, with a dark brown to reddish exoskeleton and four pairs of short legs protruding from the ventral side. Its body is flattened, covered by a hard dorsal shield that gives it a glossy appearance.
What does a fish tick look like? - in detail
A fish tick, belonging to the genus Ixodes that parasitises aquatic hosts, presents a compact, oval‑shaped body measuring approximately 1–5 mm when engorged. The dorsal surface is covered by a hard scutum, typically light brown to amber, with a slightly glossy texture. Under the scutum, the integument appears semi‑transparent, allowing the underlying blood meal to be visible as a pale yellow hue.
Key morphological elements include:
- Capitulum: located ventrally, the mouthparts consist of a short, robust hypostome equipped with rows of backward‑pointing barbs that secure attachment to fish scales or gill tissue. The chelicerae are small, serrated, and adapted for piercing thin epidermal layers.
- Eyes: two simple eyes situated on the anterior margin of the scutum; they are small, dark, and function primarily for light detection rather than detailed vision.
- Legs: eight legs emerge from the ventral side, each ending in a pair of small claws. The legs are relatively short, with the first pair often elongated to aid in locomotion across slippery fish surfaces. Leg segments are pale, matching the overall body coloration.
- Genital aperture: positioned near the posterior margin, appearing as a minute, slit‑like opening; in females, it expands during oviposition.
When unfed, the tick’s coloration is more uniform, ranging from pale tan to light gray. After feeding, the abdomen expands markedly, causing a noticeable bulge and a shift toward a darker, more opaque appearance due to the ingested blood. The ventral side may exhibit a faint pattern of fine, longitudinal striations that become more pronounced in mature specimens.
These characteristics distinguish the fish tick from terrestrial relatives, whose scutum is often darker and whose legs are proportionally longer. The combination of a compact scutum, barbed hypostome, and short, clawed legs constitutes the definitive visual profile of this ectoparasite.