ichthyo-, ichthy-, -ichth- +

(Greek: fish)

Many fishes are arranged to form a big fish representing ichthyology.
Of, pertaining to, or characteristic of fishes; having the zoological characters of a fish; piscine.
ichthism, ichthismus
Poisoning due to any toxin produced by a fish. Also, ichthyotoxism.
ichthus, ichthys
1. A representation of a fish, common as a talisman or amulet, and regarded in ancient times as a symbol of fertility.
2. The Greek word for fish was also an acronym for Iesous CHristos, THeou Yios, Soter (Jesus Christ, God’s Son, Saviour) and it is said to be the secret symbol used by early Christians to communicate with each other.

They did this by drawing a fish-like sign or symbol: This symbol is found on many seals, rings, urns, and tombstones from the early Christian period; and for some, it was a mystical charm.

Fish symbol in animation
The domain of fishes; the fish-world in all of its orders.
ichthyoacanth (s) (noun), ichthyoacanths (pl)
A sharp-pointed fish fin: Some fish can be very dangerous because they possess ichthyoacanths which are quite needlelike.
ichthyoacanthotoxin (s) (noun), ichthyoacanthotoxins (pl)
The venom secreted by a venomous fish: Certain vicious and hostile fish can use their spines or "teeth" to emit ichthyoacanthotoxin, a poison which can be deadly.
A gelatinous substance obtained from the swim-bladder of the fish, Acipenser huso. It is used as an adhesive as well as a clarifying agent. Also known as “isinglass”.
The fossilized excrement of fish.
In paleontology, a family of neopterygian teleost fishes in the extinct order Ichthyodectiformes; large predaceous fish closely related to the Osteoglossomorpha, which generally preferred a marine environment; upper Jurassic and Cretaceous.
A fossil tooth of a fish.
ichthyofauna (s) (noun), ichthyofaunas (pl)
1. All the fish that live in a particular area.
2. The fish-life of a sea or region of the sea.
An article or report written about fish.
A written description about fish.
A poison found in the blood of certain fish.
Intoxication caused by the ingestion of ichthyohemotoxin, characterized by gastrointestinal and neurological disturbances.

Other "fish" units: pisci-, Iktho Fish Story.