According to the University of California, freshwater is defined as water with a salinity of less than 1 percent. Freshwater habitats include ponds, lakes, rivers, wetlands and streams. These freshwater habitats are home to numerous species of animals and plants, including freshwater fish. The reproductive habits of freshwater fish depend on several environmental factors.
Species and Their Eggs
Species of freshwater fish include, but are not limited to: Atlantic sturgeons, brook trouts, spotted bass, yellow perches, channel catfish, rainbow trout, pumpkinseeds and green sunfish. The number of eggs produced by these fish vary. For example, spotted bass produce between 3,000 and 30,000 eggs each spring, while brook trout spawn in the fall and produce between 100 and 5,000 eggs.
Freshwater fish have different habitat preferences, which ultimately affect where they spawn, how many eggs they lay and how newly hatched fish feed and survive. One of these preferences is location. Some species of freshwater fish prefer small, slow-moving streams while others prefer large rivers with well-oxygenated water. Another necessity of spawning fish is habitat quality. This includes factors such as water temperature, water depth, available substrates for nesting, water salinity, ample nutrition for eggs and adequate cover from predators.
Egg Counts and Parental Care
The number of eggs produced by freshwater fish depends on the magnitude of parental involvement in caring for the fish eggs. This is known as fecundity. The more fecundity involved, the lower number of eggs are produced. The level of fecundity involves factors such as if the parental fish guards or carries around their eggs after fertilization. For example, male flathead catfish fertilize eggs in their nest and incubate them until all of the young leave. Other species, such as the yellow perch, provide no parental care to the 150,000 potential eggs they can produce each season. Instead, they lay their eggs under vegetation like submerged tree branches and the eggs hatch on their own after two weeks.
On the Menu
While developing in their eggs, baby fish receive nutrients from their egg yolk. After hatching, the baby fish either feed on the surface or at the bottom of their water habitat. The diets of baby fish consist of invertebrates such as insects and insect larvae, zooplankton, microcrustaceans, tadpoles, fish larvae and snails.
Freshwater Pet Fish
Common freshwater pet fish, such as goldfish, betta fish, minnows, Mollies and freshwater shark fish have reproductive needs similar to freshwater fish in the wild. For example, goldfish prefer to mate in warmer, cleaner waters with vegetation. If mating is successful, up to 1,000 eggs are produced. Species like minnows also have their own reproductive needs, such as water temperature and volume. After female minnows lay their eggs at the bottom or sides of the fish tank, males fertilize them and take over their care and protection.
- South Carolina Department of Natural Resources: Freshwater Fishes
- University of California Press: Fish Reproduction
- MarineBio: Salmon Reproduction
- Texas Parks and Wildlife Department: How Do Fish Reproduce?
- South Carolina Department of Natural Resources: Freshwater
- Goldfish2Care4: Breeding Goldfish Successfully
- University of Wisconsin - LaCrosse: Reproduction/Life History
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