This question is obvious for an ornamental fish keeper. If there is a power blackout, you will be panicking, "what happens to my fish"? Like most living creatures, oxygen is necessary for your fish. Aquarium fish require dissolved oxygen(DO), as they can absorb it directly into their system.
An air pump supplements the DO in your tank. The unit circulates water and breaks its surface tension increasing oxygen absorption. Another source of oxygen in the tank is live water plants, as they produce oxygen as a by-product during photosynthesis.
So, depending on the aquarium system, your fish can survive more days without oxygen. However, a fish can only stay for two days without oxygen in a typical tank. Also, a fish can survive 3-7 days without a filter, but this depends on the water quality in the tank.
It's not automatic to realize there are low oxygen levels unless you take measurements regularly or observe fish behavior. The best DO levels in your aquarium should be between 5-and 6 ppm. When oxygen levels lower, your fish will start swimming less active and eat less. Other fish behaviors include;
If you notice your fish having such behaviors as gasping at the surface, you should take some action. These steps include;
Several factors deplete oxygen in an aquarium.
A water filter is necessary for your tank. Depending on your fish needs and water quality parameters, fish can stay for one week without a filter. Though this doesn't mean it’s healthy to leave your fish without a filter.
First, the bacteria will die off in 30 minutes after eliminating a filter( which supplies oxygen). The fish's survival will first depend on the water depth. In a shallow tank, the fish will cause water circulation as they move and increase oxygen levels, thus staying longer.
A filter helps break down the toxic compounds into safe substances in an aquarium through a biological system. The filter also eliminates dead decaying organic matter and waste products from the water. So, when you switch off the filter, the following happens;
A filter enhances the oxygen supply in the tank for all creatures. So, removing a filter for a long time leads to oxygen depletion, and fish and other organisms may die.
A tank without a filter has a lot of waste buildup and organic matter. A large amount of nutrients causes excess algae growth.
Without a filter, ammonia and nitrate levels will accumulate to high levels. These excess toxin levels will kill your fish and lead to losses.
A filter plays a significant role in maintaining a healthy aquarium environment through beneficial bacteria. When you turn off the filter, many toxins accumulate, killing the beneficial bacteria.
Several factors affect your fish's survival without oxygen or filter. Some of the elements are the type of fish species, the tank size, and population. Some species survive longer in these conditions than others. However, it doesn't mean you should leave your fish without oxygen and a filter. Ensure you care for your creatures by providing the necessary water quality parameters and a favorable environment.