DISCLAIMER: not an official Minecraft product. This app is in no way affiliated with Majang AB. The name, trademark and assets are the property of Majang AB or their respected owner.
The add-on will populate aquatic biomes with marine creatures, both peaceful and predatory fish. Some fish you can only find in rivers, you can catch them with buckets. In total, the mod will add more than a dozen new inhabitants. The rarest is goldfish, the rest are more common - bettafish, cichlids, huge red catfish, alligator fish (predatory and will attack the player), arapaima gigas, Mekong catfish. Predators attack any fish that is smaller than them. Now you cannot tame these animals, but in creative mode you can craft a pool or make an aquarium and populate these inhabitants there and they will be your tame. Now game contains skins of mermaids and superheroes of the seas and oceans.