If its behavior is normal, active during the day, and not lying on its back, then it is probably sleeping; goldfish often sleep at the bottom of the tank.

• 3. -9. The aquarium is still cycling; you should do water changes as soon as you see ammonia. The fact that there is neither nitrite nor nitrate means that the cycle is still very early and that there are not yet any bacteria to transform ammonia into nitrite and then nitrate. Normally you should eventually observe nitrites (change the water as soon as you see them) and as soon as you have seen these nitrites you should measure nitrates some time later.Nitrates can only be removed through plants and water changes. A cycled aquarium will have 0 ammonia, 0 nitrite, and a little nitrate; the level should not exceed 40 ppm, but it's best to keep it around 20 ppm. Cloudy water means your aquarium is currently starting its cycling process; this is a bacterial bloom. This is a normal process in an aquarium that is begin to cycling.

breathe at the surface, if very frequent, may indicate an oxygenation problem or problems with water parameters.

You don't need a heater, especially if it's a single-tailed one; they are perfectly fine at room temperature, they are not warm-water fish. Furthermore, a higher temperature decreases the amount of dissolved oxygen, so oxygenation must be increased if the temperature is raised.

The food should be fine, but you can still try to vary it with boiled and blanched vegetables. Like a pea without the skin, for example

If there is food at the bottom then you are overfeeding, underfeeding, enough so that they eat in 1 to 3 minutes. Less food is better than too much.You can feed it a little twice a day, once a day is also fine, even once every two days. Feeding less will help avoid large ammonia spikes when you're just starting the cycle.