You have to take in account R&D costs, resale value, etc.
I don't see cloning fish happening. There's simply no reason to justify the cost of such a project. No a fish is not rare anymore once it becomes available to anyone/everyone.
i think cloning is less important than an intense breeding project to increase the number of rare fish. Unless you want one specific fish like li's barramundi, cloning is pretty useless and non cost-effective