Medium.
They are not a fast flowing stream species, but handle moderate flow very well. They are from slow moving streams in Asia, and these waters pass through swamps where they pick up the organic acids similar to the South American black water rivers. So if you can provide soft, acidic water with peat filtration that is the most similar to their original home.
They have been raised in captivity for so long they are quite adaptable to a range of conditions.

 

I agree with Diana regarding their natural habitat. But I can tell you from experience that they like to hang out in the filter outlet, even if the flow is > 400GPH.

 

Interesting. Mine never did. They were all over the tank, and not especially in (or out of) the filter flow.
Now if you had asked about Glass Cats... They hung out in the filter flow pretty much all the time!

 

I thik it depends on what you consider rapid to slow flow. For rapid flow I'm thinking 25 turns per hour compared to slow which would anything under 3 turns per hour. Yes in the native environment they encounter mostly slow flow however they can also handle rapid flow for short periods of time. If I were setting up a tank for them I would aim at flows between 5 and 10 turns per hour.

 

Most of my tanks were set up at about 10x, but sometimes this was a somewhat smaller filter and a powerhead elsewhere in the tank. Smaller tanks usually just have a filter, though.

 

I have a Fluval 307 (303 gal/h output) on a 40gal planted tank with wood hardscapes. When I put the filter on full blast the rasbora school towards the (strong) current then circle the tank heading back towards the current🐟🐟🐟🌿🐌
It looks like they're having fun like they're in an amusement park🎡🎢!!! I reduce the flow to a mellow stream so that my plants 🪴can straightened up

 

I have a Fluval 307 (303 gal/h output) on a 40gal planted tank with wood hardscapes. When I put the filter on full blast the rasbora school towards the (strong) current then circle the tank heading back towards the current🐟🐟🐟🌿🐌
It looks like they're having fun like they're in an amusement park🎡🎢!!! I reduce the flow to a mellow stream so that my plants 🪴can straightened up. Fluval is great

Got this model of fluval too, but with 55 gal, glad that your park is happy!