The researchers studied the fish in the Lower and Upper parts of the New Calabar River in Nigeria. They found a total of 61 different fish species, with some being more common than others. The type of fish varied between the fresh and salty parts of the river. Factors like pollution and fishing pressure can affect the number and types of fish in the river. Some fish species were rare, but this doesn't necessarily mean they are in danger. More research is needed to understand why the fish populations vary. This study can help manage and protect the fish in the New Calabar River for fishing and conservation purposes.