I did a remodel of this dolphin with more animations and better quality, check this link if you interested ---- https://www.cgtrader.com/3d-models/animals/mammal/dolphin-animated-low-poly-3d-model
The Dolphin 3d model was made in blender 2.9 ,comes with diffuse , normal , roughness and AO maps , baked 4K textures from a high poly model and place it in the low poly model , uv wrapped manually , eye, tongue and teeth (the teeth is the only one overlapping ) all is in one texture , it comes with a rig with standard bones also comes with 2 swim animations and 1 jump animation ,you can see it in the video above , comes with fbx , obj , stl and mtl format . It comes with a only animation track including all the animations , this is the timing for it , restpose 0-0,jumpanim 1-109 ,swim1 110-152 ,swim2 152-209.
if you have compatibility questions download this model https://www.cgtrader.com/free-3d-models/animals/fish/tuna-fish-9f41924a-83d4-478e-a8e9-370946f141b3 and see if it works in your project .