Use a basilosaurus to fight them. Since all their attacks involve electricity unlike the electric eels which can bite, they are doing no damage to the basilosaurus. Just spam the attack button and don’t forget to harvest their body for toxin too!
We all know that it is in shallow water and will screw all ur animals. Calm down. Just pure one to shallow water and if u do it long enough is then they will not be aggressive anymore. Unless u get in deep waters. They usually have 180 to 240 health and drop 13-14 bio toxin