Why do fishes get sick / Disease in Biofloc Tanks ??

In this video we are discussing about what are the reasons for fish getting sick / disease in Biofloc Tanks...
To learn more about Biofloc Aquaculture system (Basic) online Pls click the link below:
https://www.udemy.com/course/biofloc-...

List of video in youtube :
1 .Before investing in Biofloc System , You should Know the following ?? https://www.youtube.com/watch?v=D7jbH...

2.Biofloc Profit , Loss and investment . Know your Investment & maintenance costs https://www.youtube.com/watch?v=OMy2M...

3 .Biofloc System is failure ?? - Reasons !!!!
https://www.youtube.com/watch?v=B77SZ...

4.What is Biofloc System ?? A basic understanding. https://www.youtube.com/watch?v=Tf3Ma...
5. Important Parameters for Biofloc aquaculture System https://www.youtube.com/watch?v=VKvew...

6. What Capacity & How many Tanks to setup in Biofloc system?? https://www.youtube.com/watch?v=crbdX...

7. Biofloc Tank set up / lay out (Single & Multiple ) Graphically https://www.youtube.com/watch?v=QIVDs...

8 .Biofloc water preparation - flow Chart
https://www.youtube.com/watch?v=sldnX...

9. Evaluating fish species for Biofloc system.
https://www.youtube.com/watch?v=fShxs...

10 .Fishes/ Species for Biofloc System.
https://www.youtube.com/watch?v=pkmMU...
11.Fish Seeding and harvesting Planning for Biofloc system. https://www.youtube.com/watch?v=MjHPg...

12 .How many fishes per Biofloc Tank ??? How to calculate fish density per biofloc tank??
https://www.youtube.com/watch?v=kMXV7...
13. What is FCR and how to calculate for Biofloc system?? https://www.youtube.com/watch?v=j3kzC...

14 .Winter Season challenges in Biofloc System & How to overcome it!!! https://www.youtube.com/watch?v=k8h-i...