No doubt you have seen people keep their betta fish in a small vase. Usually it's in an ordinary vase used for flowers. It may have a peace lily oftentimes with no dirt usually floating in the vase itself. People think just because a small betta fish thrives in a rice paddie, then it can live comfortably in the just stagnant water of a flower vase. You will even read silly instructions saying not to change the water that often. I guess the thinking behind that is... a betta fish can easily live off of the plants roots and the plant can live off the betta fish waste.
Simply put... it's all hogwash, and certaintly none of it is the truth. Although betta's can sometimes live in stagnant water, they mostly live in more larger ponds and certainly cannot survive in a small vase. But if you do intend to use a flower vase or something similar then it is really crucial that you change the water as often as possible especially if you want to have a healthy and happy pet betta. Even one a week isn't really enough at all. Although your pet betta may nibble on the roots of the vase plant, betta fish do need sufficient protein to survive. And usually there is not enough nutrients in plant roots to maintain the health of a betta fish for a long period of time. So you really do need to make this vase or small tank setup work correctly for your fish to survive. Also, you need to feed your pet betta at the verty least proper and sufficient amount of food at a minimum 3 times a week.
In addition, problems you will face don't just end with the water and feeding. Even though betta fish are hardy and could survive for awhile in stagnant water, you need to make sure that they can have adequate access to the surface of the water. In other words they need to suuficiently breathe clean and fresh air. If you place a plant in the vase or tank that is too big in size the betta fish will not be able to reach to the surface of the water. This can cause the fish to suffer and not breathe correctly or sufficiently at all. However, one of the main problems with using a small flower vase is the getting the correct water temperature. Your pet betta needs to be kept at around 70-80°. If the water temperature falls below this level it could cause your pet betta to become lethargic and unhappy. Also, it will make it much more susceptible to a killer disease.
If you've put your pet betta in say a flower vase, one of the best things you could do is re-establish it in a proper bowl or tank that contains at least one gallon or more of used tap water. Then put a lilly plant in along with the fish. With this size bowl or tank both the plant and the fish will be much healthier and happier. And another thing, you will be much happier as well becuse you will not have to watch your favorite pet betta slowly break down and die.
Side point: It is not a good idea to place the bowl or tank near a sunny window in order to keep it warm because this could easily overheat the container and quickly kill your betta. In order to keep the tank or bowl water at a adequate water temperature you should invest in a relatively inexpensive flat fish heater. Try and also put a piece of glass between the bowl in the heater. This might be enough to keep a betta fish warmer through the fall in night temperature that might drop as low as 6o°. It's a really good idea to also make certain that there is something in between the heater and the bottom of the bowl. If you don't do this then it's entirely possible for the heater to crack the glass bottom of the bowl.
Now, even with all of this good information, you still need to swap the water in you pet the betta fish tank or bowl frequently to ensure that you betta has a more than fighting chance of surviving. For say a 1 gallon container you need to swap the water every three to five days or so. For the smaller 1/2 gallon vase or bowl, you really do need to change it every two or even perhaps three days. In addition, when you do need to change the water youl will also have to treat it with the correct salts and chemicals that can remove the harmful chloramines and bring the pH back to its correct level. Go to your local pet shop and you will find the best water treatments for your pet betta.
Side point:Please don't use any type of distilled water becuase it does not contain certain minerals (and, trace elements) needed by your pet betta. The very best water to use is aged tap water. But you still need to leave for at least 24-hours before using it. This will keep your pet betta fish happy and healthy.
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