The cultivation method Zhao Guang set for the Fishmen was originally intended to serve the slave contract.
This cultivation method may appear to rely on bloodlines, but it actually depends on the contract core within the bloodline.
Without this contract core, even the most intelligent Fishmen, who could learn this cultivation method on their own, would find it very difficult to progress in their cultivation. Even if they managed to cultivate successfully, the ultimate effect would be poor.
They might have a slight advantage compared to other Fishmen, but it's only a slight one.
The true cultivation method begins by relying on one's core, first repairing and perfecting the contract.
Once the contract is perfected, one can then use the contract as an aid for cultivation. Aside from needing to break through bottlenecks themselves, everything else can be enhanced through the contract.
Whether or not a bottleneck can be broken through depends entirely on one's innate talent.
