Understanding what is considered “normal” fish behavior is a key element in recognizing and treating issues with your tank. Fish not only swim, they have their own specific personalities and behaviors that they will do and recognizing them could be the different between life and death with your fish. I used to have a eel that would dart to the top of the tank, then dart back down to the bottom and then hide. The eel would repeat this behavior for about 10 minutes and then stop. This behavior was not anything that I had with any other fish that I had in the past. Naturally I was concerned and checked every possible level in the tank. After establishing that everything was normal in the tank I concluded that the eel was “playing”. The eel lived for several years and I never had any issues with it but this was my first lesson in fish behavior. This darting behavior could have been misunderstood as any number of issues in the tank and if I would not have checked the levels first I could have tried to treat the tank and fix the problem where none existed, thus damaging a perfectly normal healthy fish.

There is no doubt that Oscars are great fish and although they are very popular for aquarist they are rated in the difficult care level and should only be maintained by those confident in their aquarium skills. A few days ago we were contacted about strange new behavior from one of the Oscars tank and even though the behavior is not due to an Oscar specific illness we feel that it is a common enough issue to address.

Initially I was told that the fish was loosing its scales. The rest of the fish in the original tank were doing ok but some of them had started to loose scales as well. After asking a few questions I find out that the fish was not only loosing its scales but gasping in the water as well. After a few more questions I find out that the fish has been swimming a little “odd” when it swims at all. After talking with the owner for a few minutes to get as much information as possible about the fish I will admit that I was stunned that a perfectly healthy fish a week ago could suddenly come down with all of these issues with no new additions to the tank. All of the symptoms that I was told would be explained if there were new fish in the tank or new water added, something had to be done to contaminate the water.

Suddenly it all clicked. The person that I spoke to said that they had moved about two weeks ago. After questioning them about the move the culprit was clearly evident. When the move had taken place the owners could not find anyone to help them move the tank. So instead of leaving the tank for the next person they decided to drain the water and just refill the tank with water from the new house. MAJOR PROBLEM!!! Another factor was that all of the treatment chemicals and conditioners were packed away still and nothing had been done to the water before it was added to the tank.

The cause for all of these issues with the Oscar was Ammonia. By draining the tank and refilling it, the owner had replaced established water with new untreated water that had to go through the cycling process. Granted the filter already had good bacteria in it, but when the fresh tap water touched the bacteria it killed it and the tank was starting its process all over again. By not treating the water or testing it prior to putting it in the tank, the owner had also put in water that had a wrong pH for the fish. After talking with the owners and telling them that they needed to unpack the fish box because the water was the issue, one of the owners took a sample down to his local fish store to have them test the water which confirmed what I had told him.  I then outlined what they needed to do to treat the fish and told them that it did not look good for the fish because it was already so far along in the process but treatment would help and give the fish a fighting chance.

Knowing a normal fish behavior can tip you off to any issue that your tank is having. The owners of the Oscar noticed when they filled the tank that the behavior changed in the fish because the water was different. They wrote this change of because of temperature and the stress of the move. Granted this is a 100% over site on the part of the owners and by not treating the water they have basically killed their fish. Understanding normal behavior and not forgetting the basics is a key concept that can be overlooked and will cause havoc in the tank if not taken care of.

What is wrong with my fish? It’s swimming funny.

            Funny or odd swimming can be an indicator that something is wrong with your fish. Each issue that your fish will have will be shown through distinct behavior such as rapid and jerky movements. If you understand the definition of words such as “rapid and jerky movements” then you will recognize the behavior even if you have never seen it before.

            Odd swimming patterns can be caused by many different factors in your tank. In this article we will discuss some groupings of these issues and their treatment as well as common specific issues and their treatments. If you have specific questions that are not covered in this article please email us and let us know.

 Parasitic Infection- These infections have been grouped together because of their common causes, behaviors and treatments. If your fish has ANY ONE of these behaviors then parasites could be the cause. If your fish:

• Acts listless and appears thin and frail
• Scrapes on objects in the tank as if it is trying to scratch itself.
• Rocks back and forth in the tank.
• Gills appear red, hang partially open and pump fast.
• Darts about wildly and may smash into objects in the tank.
• Gills remain partially open at all times.
• Fins kept close to the body ESPECIALLY in live bearing fish.
• Small lumps under skin or fins (sometimes moving)
• Small black specks on the skin
• Red streaks on the fins
• Grey film on the body
• Floats with fins closed
• Thread like worms (attached to the fish)

If your fish is exhibiting any of these signs then you should get a good parasite guard and treat your tank. The causes of these behaviors range from gill parasites to head worms and can be lethal to fish.

        2. Fungal Infection- These infections have been grouped together because of their common causes, behaviors and treatments. If your fish has ANY ONE of these behaviors then parasites could be the cause. If your fish: 

• White or grey cotton like substance growing from the fish
• Fin rot
• Open sores on anabantids
• Red streaks on fins close to the body with no signs of damage
• White cotton growing from the mouth
• Flesh eaten away around the mouth
• Decay at the mouth or tail
• Frayed looking fins and moldy looking slime on the scales
• Tail eaten away with a red base on the body.

If your fish is exhibiting any of these signs then you should get a good fungal guard and treat your tank. The causes of these behaviors range from strong bacteria to parasitic fungi and can be lethal to fish.

            I am now going to cover some individual issues that your fish may have.

Flavo Bacteria infection- This infection is caused by an internal bacteria and is noticed by the fish swimming aimlessly or having jerky spasms. This type of bacteria can enter the aquarium by using a contaminated net or by the splashing of contaminated water. Treat using an internal parasite guard.

Bladder Disease- This is one of the most common causes behind abnormal swimming in freshwater fish. The swim bladder in a fish helps keep the fish level and moving in the right direction. This would be similar to an inner ear infection in humans. We count on our inner ear to stay standing upright and the fish uses its swim bladder to do the same thing. An infection to this bladder causes the fish to swim in odd patterns and not be able to control the depth that it stays in the water. Treat with a fungal eliminator.

 Below is a list of common fish behaviors due to chemical imbalances in the water.

This article is in no way a complete list of all fish ailments. This is meant as a general guide for the aquarist and a starting point to fish care. If you have specific questions that are not covered in the article, please email us and we will give you the information that you need to treat your fish.

What is wrong with my fish?

            Recently we at The Aquarium Source have received quite a few questions about why a fish is swimming funny or why it can’t swim level. These have included questions about fish swimming sideways and backwards, on their side and even a few questions about them floating upside down. In light of these questions, our writers are compiling articles about fish health and general fish care. As soon as each article is finished we will be posting them, and hopefully by giving you a better understanding about your fish we will help you keep your fish healthy longer. As there are many different issues that fish can have these articles will take a while to compile so this will be an ongoing process. If you have a specific question related to fish behavior please let us know and we will answer your question and post the article related to that specific behavior.