siamese fighting fish, originally uploaded by davidhartstone.

Though it may seem counterintuitive, smaller aquariums require a great deal more vigilance and maintenance. If you are a casual aquarist you and your fish will benefit from a larger tank.

Q: RF Wrote,

I have a betta that I’ve had for 2 months. He is only my second betta – the first one I had for 3.5 years. Who was always healthy and happy. I have been treating this betta the same as my first.

I change his water weekly and condition it. He is in a small bowl a little more than a liter. I feed him dried blood worms. Today I found him at the bottom of the tank very lethargic and it looks like he was having trouble breathing. He looks to be healthy visually otherwise – no spots, no strange fin problems. After a few minutes he started swimming and darting around.

Not too long – 20 minutes – I found him floating vertically in the middle of the tank. I have been searching all over the web now trying to find some answers to what might be going on as it is clear he is sick. He is now going in spurts of rest and spurts of swimming.

Any help or advice you could provide would be so appreciated. I read what I could on your site but didn’t find a similar problem as his bowl is always clean and it seems that fish with similar problems have been in toxic water. Thanks so much!

A: Thanks for writing in. There are couple of likely possibilities. Without greater detail into the water parameters I’m going to have to guess a bit but here are some thoughts based on what you provided. First, toxic water conditions could have lead to some sort of infection, possibly of the swim bladder causing him to not be able to right himself. Although your previous betta lived a long full life, a 1 liter contain (about 1/4 U.S. gallons) is really to small to safely house a betta. Even though the water appears clean, it’s important to remember that the presence of ammonia is completely undetectable to the naked eye. It is both colorless and odorless and in such a small container can build to dangerous levels in just a couple of days. The rate at which ammonia accumulates is different for every fish. Like people, bettas metabolize food at a different rate so while it’s possible your old betta produced ammonia more slowly (by metabolizing food) this one could be making it much more quickly. There are other factors that effect the toxicity rate as well including diet, water temperature and pH levels. Individual Bettas are also affected by their water conditions differently too. Your old betta may have had a stronger immune system then your new one. This is not to say that you have poor water quality. I can only guess based on the size of the container and the frequency of water changes. The only way to know is to test regularly for ammonia. Knowing your pH level is important too. Ammonia becomes much more toxic in “basic” water. (Water with a pH above 7.0). Here’s more information on choosing a tank for your Betta.

Choosing A Tank

Another possibility is the food you are feeding. Freeze-dried bloodworms are a good food source for bettas but alone do not make up a complete and balanced diet. They also have a very low moisture content of about 6% – 10%. A betta’s natural diet of live insects and insect larvae have a high moisture content of about 95% or higher. Once a betta eats the dry food, it can swell up with water in the fish’s gut causing blockage and pressure on the swim bladder. The swim bladder is a gas filled sack that the fish regulates in order to maintain his buoyancy. When pressure is placed on it you begin to see the fish fall to one side or most often face up. This is most often caused by overfeeding or by feeding an abundance of dry foods like freeze-dried bloodworms, flakes or pellets. Make sure you are regulating your Betta’s portions and only feeding two to three bloodworms at a time, two or three times per day. It also helps to soak dry food in tank water for about 10 minutes before feeding to allow it to soak up water before entering the betta’s digestive track. The general rule of thumb is a betta’s stomach is about as big as one of his eyeballs and that’s about how much you should provide per feeding. Another option to dry foods are live or frozen foods, which can be purchased at most aquarium stores. If you suspect this to be the problem, try fasting the betta for a day or two. You can also try feeding him some daphnia (found at aquarium stores) or the inside of a cooked pea. (Remember, just a tiny bit) These are fiber rich and act as a mild laxative. Here’s a link to more information on Betta feeding.

Feeding Bettas

Even if it’s the food that is causing your betta to be out of sorts I still highly recommend a tank upgrade. Small bowls are a lot of work to maintain because so much can change quickly. All fish do best in a stable environment. I’d recommend a small 3 or 5 gallon (11 – 19 liters) minimum for one betta. These can usually be cleaned just once per week and can be warmed with a small aquarium heater. Bettas, being fully tropical fish, need warm, stable water of about 78* – 80*F. (25.5* – 26.6*C).

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Reader Interactions


  1. Mike says:

    My Betta has just gone through a bout with a fungal infection. I looked up treatment and found the tablets that make the water blue as well as aquarium salt and a bowl heater and yesterday morning he seemed to have a complete recovery. However, late last night and into this morning he has been lingering near the top of his water (a 1gallon tank) and swimming vertically ans also he hasnt been eating since he got sick. I dont know whats wrong with him 🙁

  2. cat says:

    Ive had my femail crowntail for a week now and I come home to find her laying on her side at bottom of tank. Im very concerned shes my 3rd betta I did a water change and she has as appitite anf I do fast them 1 day a week. She has a good appitite and is very small so I dont feed her more than 2-3 pellets a day split up either 1 in the morning and 2 at night. But she also swims vertically. This all started a day ago and yes her tank is heated and stays around 78 degrees

  3. amy ivie says:

    My beta was ok until I put him in a larger tank. Now he can’t swim normal an is always floating vertically and looks to be struggling to breath. When I noticed his unusual behavior I put him back in his smaller bowl. But it didn’t seem to make a difference or improve whatsoever.

  4. Plz help says:

    My betta is laying vertically near the top of water and if I tap the tank it starts to swim normally then later gose back I had a pleco in it then took it out it also jumped out when I was feeding then I put it back

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