The introduced fish species would not become an invasive species if the fish shares a niche with the native species.
Explanation:
Non-native species are exotic species that are introduced into a different habitat and proliferate uncontrollably, threatening the balance of an ecosystem if there are no predators to contain their reproduction. In addition, these species can become a real pest, attacking native species.
One way for a non-native species not to be considered an invasive species is if it shares (and does not compete) the habitat with the native species. This occurs when the natural habitat of the non-native species is similar to the habitat being introduced and it does not pose a threat to native species.
Invasive species are successful in novel environment due to lack of natural predator or competition. Therefore if the non-native share a niche with other fish in the lake ecosystem, there will definitely be competition for resources. This could lead to competitive exclusion of one species or resource partitioning between the species consequently, the non-native fish species will not invade the new environment unchecked. I hope this helps
