Serious or not tiger barbs
 

Hey guys, so i have 5 tiger barbs in the 20 gallon cycled tank for almost 2 weeks now. They ate normally and were very active but in the last two days, i notice that one wasnt swimming with the rest and wasnt eating. None of the other tiger barbs seem to chase him off. He just seems to want to be alone and not eat. Is this something serious? Thanks

Whenever I see fish acting different, I test the water to see that ammonia and nitrites are zero and nitrAtes are no higher than 20ppm.
Have you replaced filter material or cartridges lately? Always good to clean these in old aquarium water that you take out during weekly 25 to 30 percent water changes. Cleaning the material in filter under tapwater can destroy a good portion of the good bacteria that breaks down ammonia and nitrites.

Well i havent replaced the filter since i setup the tank. So your saying to replace it?

If it's only 2 weeks old, do not replace the media. Test water parameters to se where they are.

What Lisa said.:-D

Alright, im gonna get a water test kit today asap. What if its perfect readings?

Zero ammonia and nitrites, with nitrates under 40 ppm.

If you haven't tested the water before... how do you figure the tank is cycled?!

When in doubt, do a water change with DECHLORINATED water. Chlorine is put in water to kill bacteria, and that is excactly what it will do if it goes in your tank.

In the event that water quality is not an issue...

In my freshwater days I had a lot of experience with Tiger Barbs in various tank sizes, ranging from smaller 20 gallon systems to upwards of 125 gallons. Having considerable experience with this fish, this thread caught my attention.

I think the problem you are describing in inevitable in a 20 gallon tank. Even if you are not seeing aggressive behavior, the fish sense the aggression. The weakest member of the shoal is isolated, and slowly withers away and dies. This almost always occurs in these smaller systems.

Success with Tiger Barbs really required a 55 gallon tank or larger, and either a larger school or a nice dither fish to attract the attention of the more aggressive members of the group.