First, let’s discuss the science behind a cloudy fish tank. The cloudiness is caused by too much bacteria and other microscopic life and not enough “good” bacteria in your tank eating it. This imbalance can happen for a lot of reasons. It is important to correct these issues because poor water quality can lead to a lot of health issues and even death for the fish in the cloudy fish tank.
Is the cloudy fish tank new? This is very common in newly established tanks. The “good “bacteria hasn’t established itself and things like new gravel and other substrate are kicking dust into the water. Normally this will correct itself in a week or two. If you want to help speed the process along, you can take some gravel or filter element from an established tank and put it in the new aquarium to introduce the “good” bacteria.
How much are you feeding your fish? In my experience overfeeding is the most common cause of a cloudy fish tank. If the fish don’t eat the food it sits and begins to decompose just like any uneaten food. Monitor your fish to see if they are eating all the food you give them. It should all be gone within 5 minutes. If it is not, you are feeding them too much and this is probably the culprit for the cloudy fish tank. Cut back on how much you are feeding them and this should clear up the situation. It is also a good idea to fast your fish 1 day a week. This is not just good to help keep your aquarium water clear but it is also good for the fish’s health. It allows their system to clear itself out. Just make sure you do it the same time every week. If you do mix up the days, don’t worry too much. Most fish can go up to 10 days or more without eating.
When was the last time you did a water change and cleaned your fish tank? Fish like all living things produce waste. That waste needs to be taken care of to keep the water quality good for your fish. You should do a regular cleaning of your tank once a month that includes a 25% water change, vacuuming of the gravel or other substrate, and changing of the filter medium (unless you have an Undergravel Aquarium Filter).
A cloudy fish tank is a common problem for all aquarium hobbyist. My taking the time to properly maintain your aquarium you can enjoy its beauty endlessly.