Abarim Publications' online Biblical Greek Dictionary
The noun ιχθυς (ichtus) means fish but comes with a vast footnote. The ancients were fully aware of the hydrological cycle — from the sea rises mist, mist forms clouds, clouds produce rain, rain becomes rivers, and rivers flow back to the sea — but in the same way that the hydrological cycle gives our planet a kind of proto-soul, so the reasonable mind of man was considered seated upon a much more fundamental process that ran very much alike the hydrological cycle.
The Hebrew word for waters (seas and oceans) is מים (mayim), which looks like it is a plural of the particle of inquisition מי (mi), meaning what? Mists and clouds congeal in the atmosphere and become words (Genesis 2:6; see our article on νεφελη, nephele, cloud), after which the mind of homo sapiens forms (Genesis 2:7) and begins to name things (Genesis 2:19-20). Clouds give rain, and the words for rain and teacher are the same, namely מורה (moreh), which in turn relates to the familiar name Torah, or law. Rain forms rivers that flow, and the verb that means to flow (what a river does) is the same as the verb that means to shine (what a lamp does), namely נהר (nahar).
The earliest human cultures formed by rivers (see our article on the name Tigris for more on this). That means that to the ancients, water was in many ways similar to light, and since light was in many ways similar to wisdom, water and wisdom were equally alike (which helps to explain the verb βαπτω, bapto, to baptize).
The Hebrew words for fish, namely דג (dag) and דגה (daga), hence the name Dagon, come from the verb דגה (daga), to vastly increase in number, which means that the prophet Jonah wasn't gobbled up by a whale-type creature but rather by a locust-type creature, known proverbially for the vast multitudes in which it existed.
Since angels made it into popular imagination, everybody knows that an angel is a bird-like being, with bird-like wings (and please see our article on αγγελος, aggelos, for more on this). But in the same way that angels are bird-like, so prophets are fish-like.
An angel is a being who drops information into a human mind from the outside, leading to the kind of sudden inspiration that recipients describe as clear-sky lightning. A prophet, on the other hand, is someone who intuits deeper truths without consciously knowing how he arrived at these truths, or having any tangible evidence to back them up. A prophet usually has to work hard for his insights, and then even harder to have an audience pay any mind to him. Since a truthful prophet is a valuable commodity to any society, great numbers of false prophets and performers try to dazzle the masses with smoke and mirrors (genuine prophets are fish-like and pseudo-prophets are snake-like: hence Matthew 7:10). But back when the validity of information was still a matter of life and death, a "prophet" whose nonsense didn't come true would be summarily executed (Deuteronomy 18:20).
In the Christian era, the noun ιχθυς (ichtus) or ΙΧΘΥΣ (ICHTHUS) was conveniently found to be an acronym of Ιησους (Iesous) Χριστος (Christos) Θεου (Theou) Υιος (Huios) Σωτηρ (Soter), or Jesus Christ God's Son Savior. But the mild profundity of this find doesn't baffle enough to warrant much following, and the link between Jesus of Nazareth and the image of the fish is obviously older and much more fundamentally scriptural.
Our noun ιχθυς (ichtus) meaning fish is used 20 times in the New Testament, see full concordance, and from it derives:
- The noun ιχθυδιον (ichtudion), which is a diminutive of the parent noun and means little fish (Matthew 15:34 and Mark 8:7 only). The word ιχθυς (ichtus) is also the Greek name of the constellation Pisces, which makes the seven loaves and some fishes an obvious nod to the constellation Pleiades and Pisces (the Pleiades, or Seven Sisters, show up all over the Old Testament: Exodus 2:16, Job 9:9, 38:31, Proverbs 9:1, Isaiah 4:1, Amos 5:8).