When I’m following schools of bass,  sometimes 10-15 in a school, they will fade away on the screen, almost to the point completely losing them.  You can throw to the tad bit of movement you still see and the fish will glow when they come up to your bait.  Is there any setting I need to change to keep the fish I’m chasing bright?  I keep my gain between 65 and 72.  Any help would be appreciated.  

Fish will fade as they move out of the center of the beam.  When you throw to the center a fish might swim toward your bait which will be towards the center which will make them brighter.  Remember the sonar beam gets wider further from the boat.  

I think that’s fairly typical. The fish are swimming away from you, so your beam is hitting them tail first which seems to generate weaker returns. Another factor could also be your exact settings and transducer angle relative to the dead zone or ghost tree zone on your screen. Seems like most screens have an area of weaker returns due to a number of factors. Mine seems to be more mid screen, and worse toward the bottom than the top. 

Two things....

 

1. The beam shoots out from the boat like a flashlight and gets wider the farther it gets. I think I seen at around 50 ft the beam is about 30 ft wide...   your fish are probably on the edge of the beam and as they leave the beam they fade away on the screen and as they reenter the team they show up again...

 

2. Also, as fish are swimming away or towards you in line with the boat, they are narrower, so they aren't as bright. As they turn sideways and you are hitting the side of them with the beam they will also show up brighter because you know, a bigger target...   Hope that helps