While there are some species that naturally hang out on the bottom of the fish tank, bottom sitting is normally an indication of fish problems in your aquarium. Fortunately, they are normally relatively easy to fix if they are caught in the early stages.
1. The water quality is poor.
This is the first thing that you should check if any of your fish are exhibiting abnormal behavior, like sitting on the bottom of the tank. A quality water test kit is one of the best investments you can make if you’re serious about keeping your fish – I can’t tell you how many times I’ve had to test my water in an emergency situation in the middle of the night, well after the pet stores are closed.
If you have the chance, pick up a liquid test kit because they will provide you with more accurate results. However, any test kit is better than not having one when you need it the most – the quick dip test strips work perfectly fine as well. If you can’t afford to purchase a test kit right now, most pet stores offer free water testing as a courtesy service – at the very least, make sure you have them test for ammonia and nitrite.
However, sudden changes in pH will also cause fish problems, and hard water will amplify the effect of the ammonia and nitrite present in your tank. I routinely check the ammonia, nitrite, nitrate and pH in my tank every week so that I can track changes as they happen and prevent problems with my fish tank before they even happen. If you suspect that poor water quality is the culprit, then immediately conduct a water change, and check to make sure that the filter is still working properly.
2. Your fish is sick.
When fish are not in good health they will become lethargic and sit on the bottom of the fish tank – clamped fins are a good indication of an illness, however, they can be the result of general stress as well. There are many different types of fish diseases and ailments that can cause bottom sitting, like fungal infection, parasitic infestations and bacterial infections – the beginning stages of fish ick will often present as bottom sitting.
3. Your fish is in an improper environment.
This is another common reason that fish sit on the bottom of the tank – typically, they will perk up again once the situation is remedied. An example of an improper environment would be schooling fish kept singly, like tetras and barbs. Schooling fish are not meant to live as single fish, or even in groups of three, and will often act lethargic if they are alone. Additionally, you should ensure that you have a large enough fish tank set up for your fish.
A bored fish will quickly lose the desire to swim around and show activity – a tank that doesn’t have enough plants and hiding places does not create a very interactive environment, and will easily lose the interest of your fish.
You can prevent most cases of bottom sitting by performing large, frequent water changes at least every week, setting your fish up in a proper environment, and practicing proper quarantine procedures for all new tank additions.
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