Goldfish like any other pets require care and attention in order to stay active and happy. Their requirements are basically more or less the same just like any other fish species and their basic necessities like clean, oxygen-rich water, plenty of swimming space, food, and correct water temperature all are very important and for that, it is your responsibility to ensure that those are fulfilled. Before I move on further, it would be helpful to first learn and get yourself introduced to this wonderful fish species (a look at panda, jikin and ranchu).

Based on my observation, what I can see also is that your pet goldfish which are deprived of normal day and night cycle will end up having slower growth rate. This has been backed up before by scientific facts because although goldfish do not have eyelids, they are known to stay idle during certain times to rest and recuperate. Therefore, when the lights are out, it is the best time for them to take their precious break and if possible, try to create a planted aquarium tank for your fish to live in and hide. Generally tank environment that have community of live plants are known to make your fish feel at home and overall it helps to improve their health.
Goldfish that are kept happy are always active and have a hearty appetite. They will display their full body coloration which is bright and attractive and you will be amazed how those colors develop so quickly. Your pets when they are in a good mood will also breed to reproduce young babies. In fact, this is the most exciting part dealing with goldfish care and believe me, it is very challenging process learning about how they grow from a small tiny little fry to become a gigantic full grown fish. You will be impressed by how all these come together and it is your role as an owner to ensure that nothing is lacking. Sometimes it just makes you wonder what else further you can do to make them happier.
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