Answer:
Due to suitable environment of the equator.
Step-by-step explanation:
Latitude is abiotic factor that has a great impact on the occurrence of fish species as we can see in the graph, the fish species increases as we go towards equator whereas decreases when we go away from the equator. This is because the climatic condition and temperature of water at the equator is suitable and warm so this suitable environment attracts more species to lives there.