What Are Baby Fish Called at Birth?

Most people can easily answer the question “What is a baby dog called?” or “What is a baby pig called?” But what happens if we ask, “What are baby fish called when they are born, and in their earliest life stages?” Like other animals, fish offspring also have a specific name, though it is used less often in everyday language and therefore more easily forgotten. In this article, we explain what baby fish are called, how fish reproduce, and why the term fry (Spanish: alevín) is applied across species.

What Is a Fish?

Fish are aquatic vertebrates characterized by:

• Fins for locomotion.

• Gills that extract dissolved oxygen from water, functioning much like lungs in land animals.

• Scales (in most species) that provide protection.

Fish are highly diverse, ranging from tiny tropical aquarium species to large marine predators such as tuna or great white sharks. They can be found in:

• Freshwater ecosystems (rivers, lakes, streams), e.g., trout or carp.

• Saltwater ecosystems (oceans and seas), e.g., cod, tuna, sharks.

• Cold-water or migratory species, such as salmon.

Thus, when we speak of “fish,” we are referring to a broad and varied group of animals rather than a single type.

How Do Fish Reproduce?

Fish reproduction varies across species, and three main modes are observed:

1. Viviparous (live-bearing) reproduction

• Fertilization occurs inside the female.

• The female gives birth to live, fully formed young.

• This method is uncommon among fish but occurs in some sharks and rays.

2. Ovoviviparous reproduction

• Fertilization is internal, but the female releases fertilized eggs.

• The embryos develop inside the eggs until they hatch, often within or just outside the mother’s body.

• Rare in most fish, though it occurs in certain marine species.

3. Oviparous (egg-laying) reproduction

• The most common method.

• Females release eggs into the water, and males fertilize them externally.

• The eggs then develop outside the mother’s body until they hatch.

• Most freshwater and marine fish reproduce this way.

What Are Baby Fish Called?

Regardless of the reproductive strategy, baby fish are called “fry” (Spanish: alevín).

• “Fry” refers to fish that have left the egg (or the mother, in live-bearing species) but are not yet sexually mature.

• They are small, fragile, and still developing, but capable of swimming and feeding independently.

• Sometimes the term “fry” is used even before hatching, if the embryo inside the egg is already well-developed and its body form is visible.

Thus, whether salmon, carp, tuna, or sharks, all young fish are universally called fry.

Why Only One Term for Fish Offspring?

In many animals, baby names are species-specific:

• Horse → Foal

• Dog → Puppy

• Rabbit → Kit

• Pig → Piglet

But for fish, the term fry is used for all species. This is not due to biological necessity but rather linguistic evolution:

• Humans needed specific words for the young of animals closely tied to daily life.

• Since fish live in water and human interaction with them was historically less direct, a single generic word was enough.

Conclusion

• The offspring of fish, from the moment they hatch until they reach reproductive maturity, are called fry.

• Unlike mammals or birds, fish do not have species-specific names for their young.

• This simplicity in naming reflects human language habits rather than biological differences.

So, the next time someone asks, “What are baby fish called?”, you can confidently reply: They are called fry!

animal tags： fry