why is my fish swimming up and down

It is not uncommon for fish to swim up and down the glass but may appear to be something to be concerned about. This is normally not something to worry about though. You will often find this is done in the corner of the aquarium and the reason why fish may be doing this is due to following their reflection or simply of boredom. Although we think of our tropical fish as fairly intelligent animals, a reflection is something which may confuse and excite them in to constant swimming up and down the glass. This fish behavior is normally observed when a fish is first introduced to the aquarium whilst they are trying to find their feet and way around and will normally stop after some time, normally a week or so.


It is also common to see fish fry and younger fish swimming up and down the glass playing with their reflection, they are still young though and learning the ropes as it were, again, nothing to worry about. If there is little else in the tank then give the fish something to swim in and around so they can keep themselves entertained such as plants, wood and rocks (depending on the type of fish you keep). The only time it may be worth looking further in to if your tropical fish swim up and down the glass and do not appear to be eating.


As with most fish disease and issues, lack of feeding is always cause for concern although the swimming up and down the glass may just be something they would do anyway. It could be worth changing type of food if they are not eating and are a new introduction to the tank however immediate action may not be required, most tropical fish can go for weeks without food so closer observation is advised to see if there are any signs of other stress related diseases. In summary, if your tropical fish is swimming up and down the glass constantly there is nothing to worry about, they will soon work out they cannot do anything with their reflection and settle in to the tank and environment.
I have seen a lot of these types of questions as well and the most common answer I have read is I dont know!.


Some suggestions have been that the fish may be acting this way because of a recent change in decorating of the tank or a new addition to the tank. I have also heard that this could be due to a the fish having a less than dominant postition in the tank. However, I do not think that it is completely weird because I have seen this behavior alot in my own tank and I have seen this question posted alot.


I would say that if your water parameters are all normal and your water quality is up to par as for the fish you are keeping, this could mean absolutely nothing or at least nothing important enough to worry about it. Maybe it is the fish s reaction to the fish you had die being gone. Oh, I have come to the assumption that my livebearers do this alot because I have a bubble curtain running in the tank. I turned it off one time out of curiousity and they quit doing it about a day later.

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