In Jainism, there is no fixed number of organisms in water. The tradition teaches that water is populated by innumerable jivas (sentient beings), ranging from very tiny micro-organisms to larger deha-sadhak beings. Because jivas are countless and can exist in many forms, there isn’t a specific tally given in the scriptures. The emphasis is on nonviolence and reverence for all life, even the smallest living beings in water.

Note: Different Jain traditions (Digambar and Śvetāmbara) may have slight variations in classifications, but both affirm the principle of innumerable jivas in aquatic environments. If you’d like, I can provide a brief summary tailored to Digambar or Śvetāmbara views.