I can't really tell much from the picture due to the camera focusing on the background instead of the fish. However, the fish's fins are tail are all open and looking normal shaped so that is usually a good sign.
If you lost a fish, test the water for ammonia and nitrite and then do a 75% water change and gravel clean every day for a week. If you don't have a test kit, just do a 75% water change and gravel clean the substrate every day for a week. This will remove any ammonia, or nitrite that might be in the water, along with any disease organisms that might be in there.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
If more fish die, try to get some photos of them that are in focus and post them on here. But the biggest cause of fish deaths is poor water quality so do water changes and monitor the ammonia and nitrite levels.