FOOD OF FRESHWATER BABY FISH

Freshwater baby fish eat a variety of invertebrate animals. When they start to eat, after absorbing their yolk materials, they eat small organisms such as dinoflagellates, copepod nauplii, fish eggs and others. As they grow larger, they eat larger invertebrate and vertebrate organisms. When baby fish are large enough, they will even eat other baby fish and then gradually develop the innate food habits of their particular species. Below are examples of several food items of baby fish within the freshwater environment.

Figure 1) Cyclopoid copepods live in many different freshwater bodies; some are limnetic and others live along the bottom. For feeding, cyclopoids seize their food with their grasping arms and mouth parts. Females carry egg sacs and the eggs hatch into naupliar larvae. The specimen shown above is in the genus Cyclops.
Figure 2) Calanoid copepods live in many different freshwater bodies; most are limnetic but a few live along the bottom. Calanoids are mainly filter feeders for particles of food are brought into their mouths with currents of water created by their moving mouth parts. The specimen shown above is in the genus Diaptomus.
Figure 3) Harpactacoid copepods live in many different freshwater bodies; most are benthic or littoral, living within aquatic vegetation or on the mud and debris along shores. Harpactacoids seize their food with their grasping mouth parts and eat it. The specimen above is in the genus Canthocamptus.
Figure 4) Cladocerans, like Daphnia, live in limnetic areas of lakes. They live in all types of fresh waters except rapid streams and polluted waters. They carry parthenogenetic eggs in dorsal cavities of their carapaces. They feed on limnetic algae and detritus. The cladoceran specimen shown above is in the genus Daphnia.
Figure 5) Cladocerans, like Chydorus, live in all types of fresh waters except rapid streams and polluted waters. They carry parthenogenetic eggs in dorsal cavities of their carapaces. They live among aquatic plants where they feed on algae and detritus. The cladoceran specimen shown above is in the genus Chydorus.
Figure 6) Cladocerans, like Bosmina, live in all types of fresh waters except rapid streams and polluted waters. They carry parthenogenetic eggs in dorsal cavities of their carapaces. They live among aquatic plants where they feed on algae and detritus. The cladoceran specimen shown above is in the genus Bosmina.
Figure 7) Phantom midge flies (non-biting midges with hairy wings in the family Culicidae) lay their eggs on the surface of water bodies where they hatch into larvae and then swim to the bottom. Their larvae spend most of their time on the lake bottom, coming to the surface only at night where they prey on small crustaceans and other insect larvae. The specimen above is a phantom midge in the genus Corethra.
Figure 8) Nauplii are the larval stages of copepods and some other crustaceans which hatch from eggs. Male copepods transfer sperm to females in small packets. Most copepods carry egg cases from where nauplii hatch. The nauplii develop and molt numerous times before becoming mature copepods. Nauplii live free in open waters. The specimen above is a ventral view of a first stage nauplius of a copepod.
Figure 9) Ostracods are found in all kind of water bodies but are usually found in depths 1 m or less. Most species creep around within algae or over aquatic plants but some species live in the open limnetic area. They lay their eggs along twigs, rocks or plants and emerge as nauplii (see copepod nauplii on left). The specimen above is a lateral view of an Ostracod in the genus Cypris.