My Goldfish are trying to swim up stream...

Question
I recently built a waterfall behind my pond which is around 185 gallons.  When the waterfall is on, my goldfish are going crazy.  The smaller ones actually jump out of the water like the are trying to get on top of the water fall and the bigger ones try to push themselves up the side underneath it.  The bigger one usually cannot get more than half way out of the water but the smaller ones have almost made it on top of the rock.  I am hoping that this is not because there is something wrong with them. My husband thinks that they are just playing.  Have you ever heard of fish doing this before?

Answer
Hi Shannon,

It's not uncommon for Fish to try and swim against the flow of water. However, the Goldfish is native to the still and slow moving waters of Southern China.

Fish like Danios, White Cloud Mountain Minnows etc are native to fast streams so when a venturi line is placed in an Aquarium they will throw themselves into the fast stream of bubbles. Yet, it is not unknown for Goldfish to do exactly the same thing. Even my Goldfish tend to shoal around the filter, taking it in turn to check themselves against the return valve.

I'm not entirely sure what does this, perhaps it's mating instinct. Perhaps it is purely just playing. Who knows? however it's nothing to worry about.

Tom