The new Deep Blue Wise One Bloodline the Fishman youth had acquired was only of Bronze Level, and not of a high grade.
Fishmen with this type of bloodline were completely incompetent in cultivating fighting energy and as spellcasters, their achievements would be limited to Bronze Level for life.
In most cases, bloodline defined one's talent and aptitude for cultivation.
Some bloodlines were extremely proficient in cultivating fighting energy, like the Martial Sect Bloodline of the Holy Bright Empire. Others excelled in the realms of magic or Divine Arts, like the Angel Bloodline.
There were also some that encapsulated multiple categories, such as the Flame Dragon King Bloodline absorbed by the youth. Transcendents with this complete bloodline found it easier to make accomplishments in both the domains of fighting energy and magic.