It Depends on the Situation
Whether a betta fish needs a filter mainly depends on the breeding environment and the frequency of water quality maintenance. The specific analysis is as follows:
Key Influencing Factors
Breeding Density and Fish Tank Size
When a betta fish is kept alone and the fish tank is relatively large (it is recommended to be more than 30 cm in size), the metabolic rate of the betta fish is low. The labyrinth fish characteristic allows it to breathe air directly, so it has a relatively low dependence on the filter.
If the fish tank is small or the breeding density is high, the filtration system can effectively reduce the risk of water quality deterioration and avoid the accumulation of ammonia and nitrite.
Water Flow Adaptability
Betta fish prefer still water areas in their natural environment. If the water flow of the filter is too strong, it may prevent the fish's fins from fully spreading out, affecting its ornamental state. Choosing a low-flow filter (such as a sponge filter) is more suitable.
Daily Maintenance Habits
If you can change the water regularly (for example, replace one-third of the water body every week) and manually clean up the residues, you may not need a filter.
If the maintenance frequency is low, the filtration system can extend the time of water quality stability and reduce the frequency of water changes.
Summary of Authoritative Suggestions
Situations Where No Filter is Needed: When a betta fish is kept alone, in a large tank, and the water is changed frequently, you should give priority to considering the characteristics of labyrinth fish.
Situations Where a Filter is Recommended: When the tank is small, the breeding density is high, or the maintenance frequency is low, you need to pay attention to choosing low-flow equipment.
If you need to further optimize the situation, you can combine water quality maintenance with the fish tank's ecological cycle plan to balance water flow and water quality management.