The Soshentar River is split into three biomes that come with different fish. The map above shows the borders and the corresponding types. In the south (and possibly also in the north) part of the river there’s a small strip where two biomes overlap. Fishing there actually nets double rewards, one fish from each biome. We think it’s not intended, but if you’re not looking for a specific catch for your collection, this is the spot to make most out of your bait.
The basic bait by the way is only able to catch fish up to tier 4. For tier 5 fish you need to farm the Glowworm that drops from the flower nodes around the map.