Taming Creatures On a Whale or God of Fishing? I know there's a possibility that none of these two novels you're looking for but maybe...
no, it could have also been the equally popular webnovel "Lout of Count's Family" is there anything special about the whale or what it does?
the wale is a old and powerfull demonic whale that the mc beats and the mc make the whale pull his floating island
MC of Trash of the count's house becomes friends with Huge Whales but the said whales have human forms