Yes, rockfish can easily be overcooked. The ideal internal temperature for fish is 145 °F (62.8 °C), as per USDA's guidelines. The problem with delicate fish such as rockfish is that even 5 degrees above can lead to dried-out meat so it is less forgiving than pork, chicken, or beef. Overcooked rockfish will still be flaky but drier and with a more rubbery texture. Use a quick-read meat thermometer to get an accurate reading of the internal temperature and remove the fish from heat as soon as it reaches 145 °F to avoid overcooking it.