In fertilized fish ponds, phytoplankton density is a more immediate indicator of fertilization program efficiency because it reflects the level of primary production, which directly supports fish growth. High phytoplankton density indicates effective nutrient utilization. However, phytoplankton biodiversity is also important for long-term pond health, ensuring ecosystem stability and preventing issues like algal blooms. While density is crucial for short-term productivity, biodiversity contributes to sustainability and resilience. Therefore, a successful fertilization program should aim to balance both density and biodiversity.

In fertilized fish ponds, phytoplankton density is often prioritized initially to ensure high primary productivity and maximize the use of available nutrients. However, biodiversity becomes equally important in maintaining long-term pond health, preventing eutrophication, and providing balanced nutrition.

However, under some circumstances there is a conflict between density and biodiversity of algae among fertilizing programs, so in this situation which would be better and more desirable.

Some literatures also showed that some treatments have high algal density with low diversity, while others have low density with high biodiversity.

Phytoplankton density is the more important indicator of fertilization efficiency because it directly shows how well nutrients are being used to boost fish production. More phytoplankton means more food for the aquatic food chain, better oxygen levels, and overall pond productivity.

However, biodiversity still matters—it helps keep the ecosystem stable, prevents harmful algae from taking over, and ensures a healthy food supply. So, while density is the key measure of fertilization success, a balanced mix of phytoplankton species is also important for long-term pond health.