What Do Little Fish Go By?

A baby fish goes through numerous phases throughout its existence. In the early years of their existence, they go by a variety of names. The names and developmental phases given to baby fish vary depending on the species. Before they reach adulthood, this can include eggs, yolk-sac larvae, fry, and juveniles.


The three methods of fish reproduction are as follows. Either livebearing, which is how people and other mammals generate their young, spawning, or self-bearing are used to accomplish this.

When a female fish releases her eggs, this is referred to as spawning. The eggs are either placed into a nest or are dropped directly into the water where they float about. Depending on the species of fish, yes. The eggs will then be fertilised by the male fish’s released milt. Not all deposited eggs will become fertile. Depending on the species, fish may spawn annually, every four years, or just once before passing away.

A few fish can change their gender. This enables them to finish the entire reproduction process independently. The term “self-bearing” also applies to this technique.


In two to eight days, depending on the fish species, fertilised eggs begin to hatch. Due to the various hazards they encounter, the majority of eggs never mature. One of these dangers is the shift in water temperature that can take place during spawning as a result of the varying seasons. Another frequent threat to fish eggs that have been fertilised is the water’s oxygen levels fluctuating. The egg will not hatch if sedimentation or flooding transports it to unsanitary places or renders it landlocked. Fish are always at risk at every stage of their life cycle from predators and disease.


Nine to 18 days after an egg has hatched, a newborn fish enters the larval stage. Due to the fact that the yolk-sac remains linked to the young fish after hatching, this phase is also known as the yolk-sac phase. The baby fish receives the nutrition it requires from this yolk sac to develop in its natural habitat. Catfish and other fish species don’t go through this stage.

The newborn fish’s larval stage lasts one to two weeks. It remains at the bottom of the water throughout this time and feeds on the yolk-sac. Many fish species have a tendency to settle in the vegetation and other caverns at the bottom of the water when they are in the larval stage in order to find protection. As they are considered free floaters and lack swimming fins, this enables them to blend in and hide from predators.


A baby fish’s yolk sac is still attached when it is a fry, but it starts to get smaller. For the majority of fish species, the fry stage lasts two to five days. Throughout this period, the fry will remain at the water’s surface. It does, however, start to investigate its new environment and occasionally emerges from concealment. A fry gets the majority of its nutrients from the residual yolk-sac, although it will start eating food that is at the water’s surface.


The length of time the young fish remains a juvenile depends on its species, as it does with each stage of a fish’s life cycle. Up to three years could pass during this stage. The gills develop during this stage, and the fish’s fins start to develop. Fish that are young cannot reproduce. The fish must learn how to survive among its predators, obtain enough food to survive, and develop its independence in all other areas from the start of the juvenile period if it is to survive.

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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