You may add more fish now but do it slowly. Too many fish added at once can still produce ammonia spike in an aquarium you just cycled with fish. It is a good idea to add no more than one fish at a time if you had only one fish in the tank by the end of fish-in cycle. If you have more than one fish survived the fish-in cycle, it is still recommended to add only 1/3 of the existing number of fish at a time. In both cases, please wait for at least a week or two before you add more fish. You must also continue to do testing on the aquarium water for ammonia, nitrite, and nitrate. If there is any sign of ammonia or nitrite, you must immediately do a partial water change with Prime, and repeat it every 48 hours until there is no more ammonia and nitrite.
Never..and I mean NEVER cycle an aquarium with fish
So to start with, what is cycling? To put it as simply as possibly, cycling an aquarium is the act of building up beneficial bacteria in an aquarium, that break down the fishes waste. Some people may remember the nitrogen cycle from high school science class, and this is a limited version of that occurring in the tank.
Fish-in Cycling: Step over into the dark side
The advantage of cycle with fish.
You get to have the pet fish immediately after you set up your aquarium. Many people can’t wait to get their hands on the fish the moment they set up their aquariums, therefore this might be seen as an advantage for some people.
How to Cycle a Fish Tank (with Pictures) - wikiHow
The process known as cycling is a way of cultivating necessary bacteria in a new aquarium. The bacteria are necessary to decompose the waste products produced by fish and other inhabitants in the aquarium. An aquarium will always need a combination of suitable bacteria cultures and frequent water changes to stay clean and provide the fish with a good environment. If you add fish to an improperly cycled aquarium they can quickly fall ill or even die, since their waste products will pollute the water. Some fish are more tolerant to moderate levels of soluble waste than others, but no fish will appreciate an aquarium with high levels of these toxic compounds.I would encourage all fish keepers to gain an understanding of the nitrogen cycle as this will help you understand exactly what is going on inside your tank and how you can deal with water quality problems should they arise.The simple answer is yes, an aquarium must be cycled properly before you can safely add your fish. It doesn't matter whether the tank is 15 gallons or 500 gallons, it's still got to be cycled. If you were to simply fill your tank with water and then add all your fish at once then there would be such a massive buildup of ammonia, the chances are your fish would be dead within a few days.Traditionally, there are two ways to cycle a fish tank. Both methods will involve introducing ammonia into the tank which will be the food the bacteria need to survive. The most common method of cycling an aquarium is to use small community fish that produce the ammonia themselves. A kinder, more acceptable way to cycle a fish tank is to use a method called the "fishless" cycle. This also involves adding ammonia to the aquarium, but as a name suggests you do not use live fish. In this article, we are going to use fish as it's probably easier for a beginner to undertake, and we wouldn't be happy with youngsters handling pure ammonia as it can be dangerous. If you would prefer not to use live fish then read this article on how to carry out a fishless cycle.We would recommend that you use small community fish like the Barb. The Tiger and Cherry Barb are absolutely ideal as they are quite a hardy species of freshwater fish and unlike some more sensitive species, won't turn belly up as soon as they are exposed to ammonia. If you are cycling a very small tank less than 20 gallons then you are probably better off using much smaller fish like guppies or neon tetra. Your fish store should be able to give you advice based on what fish they sell.It's important not to add too many fish as this will create a large ammonia spike very quickly which will probably just kill the fish within a few days. For a 55 gallon tank, 10 barbs would be appropriate. For a 75 gallon tank, you could go up to 15, for 100 gallons plus, you're looking around 20 upwards.It's become quite popular to kick start the cycling process by seeding your new aquarium with biological media that already contains live nitrifying bacteria.