The color is a little yellow, which indicates a need for food; give them a light feeding, preferably in a solution into which you can dip the seedlings, thus avoiding the potential for damp off when watered/fed from the top.

Start fertilizing at 1/2 the recommended rate when the first TRUE leaves develop. When the seedling first emerge from the soil, it is being fed from the energy stored in the seed, and then from the cotyledons. The cotyledons feed the seedlings until the first true leaves, then the cotyledons die back. Water and fertilize early in the morning, then set the container in the sun so that the soil surface quickly dries out. Doing so will greatly help to prevent the fungus rhzoctonia (stem rot), which is the number one killer of young seedling.

Why not fertilize at full strength?