Growing Up

Our salmon have changed greatly since we got them. Their sides have gone from clear to silver/green with stripes. They are also much more active. Their yolk sacks are getting smaller. They have also grown longer.  They used to be more active when it's light, but now, they are more active when it's dark.
One fish in particular has built up strength so that it can almost swim to the top of the tank. We even witnessed that one swam to the top and stuck his head out of the water. Our hypothesis is that this fish was getting air to fill his swim bladder. They are acting more like older salmon by beginning to form schools.  We've observed how they collect in the corners of the tank.