If you arent going to do regular maintenance, keep it to 5 or less godlfish.
One goldfish requires 20 gallons on it's own, not only due to the size it can grow, but because they are very high waste producers.You can look at getting one betta for a 1 gallon tank, but be sure that you clean it at least once a week, twice if necessary.
Keeping the water clean in your goldfish aquarium will not only make your fish more likely to spawn but will also greatly improve the health of your fish and any potential fry, so yes you should keep your goldfish's water clean for them to spawn.
I have a 75-gallon tank and clean out about 10 gallons every week. Since yours is an 18 gallon tank, I would start with cleaning it every two weeks by siphoning the substrate and removing and replacing 7 gallons. If your water looks dirty try changing 5 gallons every week. But I think you will be good with the two week option.
Unless you expect it to just swim around in a bowl. It helps to CLEAN IT every once in a while.
Provided the tank does not leak and it has been thoroughly cleaned there is no reason why it should not be suitable for keeping fish in.
I have a 75-gallon aquarium and I remove debris and change out 10 gallons of water once a week. So if you have an an aquarium clean it once a week and replace at least 10% of the water weekly.
Use a filter and try not to give it too much food. Sometimes it won't eat all the food and the water will cloud up faster from the dissolved food. also it depends on the tank if its big one you could buy one of those suker fish to clean it for you they wont kill your fish and you never have to feed them
Individuals with goldfish must regularly clean the fish tank. The water should be kept at a slightly alkaline pH and the temperature should not exceed 75 degrees Fahrenheit. Lastly, the owner should be careful not to underfeed or overfeed.
goldfish aquarium maintenance can be divided into several sections: weekly: scrub sides of aquarium with a sponge, if there is green alge living on the sides then do not disturb it for your goldfish will enjoy snacking on it and the alge also serves a purpose: during the day it participates in photosynthesis thus creating oxygen therefore raising the dissolved oxygen levels in the aquarium. If you do use gravel in your aquarium then you will want to use a siphon to vacuum the gravel each week, however vacuuming the gravel does disturb the colony of nitrosomas and nitrobacter bacteria living there which help aid in biological filtration therefore I suggest only grooming about half of the gravel bed each week. Also do around a 25-50% water change of your tanks water each week, this will help keep the water clean/clear and is extremely good for your goldfish. Every two weeks: If you have a sponge filter or poor filtration it is a good idea to rinse it out in a bucket of aquarium water every two- three weeks. Monthly: Rinse out any filters in a bucket of aquarium water, scrub any tank ornaments with a sponge, whipe off the top lid of the aquarium (do not use any cleaning sprays/ agents that are not labled for aquarium use! or you might kill your fish) Also be sure to clean off any tubing or other equipment used inside your aquarium.
It depends how big your aquarium is. I would start with a few bags cause you can always buy more, Just work your way up until you think you have enough sand.
Every Second! Gold Fish are Very messy and need a filter to keep them alive. I suggest you put your Goldfish in a pond. Make sure there is more than one, Goldfish have friends just like you and me. Or you could get a 20 gallon tank (the tank has to be big enough so goldfish can grow up to 10 inches long WITH a filter. okay long story short, one inch per fish needs at least a gallon!
every other week