Bully Fish

Question
Hi Chris,

my tank is 5 gallon, I have 3 Zebra Danios and 4 White Clouds.

One of my danios seems to have very aggresive behaviour. It keep chasing the other 6 fishes there, one by one.  Is this normal? It dominates the whole tank and all the fishes runaway when it comes near them.

When I feed them, the 3 danios are going crazy and eat all the food. I'm afraid the white clouds don't get anything. They only get the small crumb leftover.

If I get more fishes, like bigger ones, will this stop the bullying behaviour? Is Barb a good choice?


Thank you,

Pauline.

Answer
Hi Pauline;

Your best solution is to give the aggressive one away. Donate him back to the fish store or even get him his own little tank. The 5 gallon is already overcrowded and adding more fish will be fatal to them all eventually. You might consider adding live plants to help consume some of the waste, add oxygen and also give all the fish places to hide when they need it.

Barbs need a much bigger tank no smaller than 20 gallons. Barbs should be in groups of 3 or more so they keep their aggression within their group amongst themselves. If there are one or two barbs they will be very aggressive to the other fish in the tank.

My main worry in your little tank is the overcrowding issue. A 5 gallon can only hold a total of 5 inches of fish safely. White clouds and danios get 1.5 inches each as adults. This make a population total of 10.5 inches or twice the safe population limit. Yikes! You will need to do lots of water changes just to keep them alive as they grow. Replace 25% of the water twice a week. Vacuum the gravel every couple of weeks too.

Another solution is to get a 10 or even 20 gallon tank for the danios and white clouds. Keep the 5 gallon for the little 'devil danio' and give him maybe a couple of cory cats to keep him busy. Danios are upper tank fish and cory cats are bottom fish so he won't bother them.

At Your Service;
Chris Robbins