You should schedule partial water changes once every 3 to 5 days to ensure that your fish live a healthy and happy life in their unfiltered tank. Fish can live without a filter, but they certainly can't survive in murky, oxygen-free waters. Fish can survive in an artificial environment without a filter for approximately 3 days to a maximum of one week. The number of days depends mainly on several factors, such as the number of fish, the measures you are going to take to ensure filtration, the resources you have and the alternatives.
As a downside, you should rely on water changes to keep them healthy. The real problem here is that the filter will also improve the oxygenation level of the water, in addition to cleaning the water and removing ammonia. Without that, your fish will suffocate and die. In addition, the chance for a fish to live well in an aquarium without a filter is quite high, since it can adapt to any environment relatively quickly.
Goldfish are cold-water fish and if you keep the temperature below about 20 degrees Celsius, the water will be able to retain more oxygen than warmer water, making it easier to keep fish alive. According to an experienced aquarist, this fish has the ability to survive in a fish tank without a filter. These include the type of fish in question, the number of fish in your aquarium, the acid and bacterial level of the water, other filtration methods, and the resources it has to offer. Guppies are the most popular choice among fish lovers because of their unique color, friendly attitude and ease of maintenance.
The fact that lakes are large enough to ensure that fish live a healthy, oxygen-filled life means that the waste and toxic chemicals that are released dissolve and the water is safe for fish. However, you should ensure that your aquarium has sufficient bacterial growth before putting your fish in the water tank. This type of fish is one of those species of fish that doesn't produce much waste, making them perfect for an aquarium without a filter. Regarding its physical structure, this type of fish is popularly known as a rainbow fish because it comes in a wide range of colors that resemble the rainbow.
Some fish can live in unfiltered water for an indefinite time if the aquarium has a large number of plants. In addition, they are also an excellent solitary fish that has the ability to entertain themselves if you give them the right waterscaping configuration in your aquarium. These steps should help you save your fish in time and give them a happy life forever (unlike the innocent, clueless fish found in a fish tank). Gourami species are very popular among aquarium caretakers, as they are adaptable, resilient and require minimal maintenance.
However, this entire condition can put a fish under a lot of stress and make it difficult for a fish to survive without oxygen.