Aquarium Setup Options

[MentholLite]

Hi guys,

I am a newbie in goldfishes.

Recently, I have been doing alot of research on rearing goldfishes (water cycle and condition, goldfish diseases, etc).
I read that per goldfish actually needs 38 litres of water each. Am I crowding the goldfishes given the current tank volume?
In addition, is the current water flow (~1200litres/hr) too strong for the goldfishes?

Below are the picture and attributes:


Aquarium Setup

CODE

Tank Capacity = Length (cm) * Width (cm) * Height (cm) / 1000
              = (120 x 40 x 50) / 1000
              = 240 litres (65 gallons)

Current Water Volume = (120 x 40 x 30) / 1000
                 = 144 litres

Filtration: Jebo 828 28W 1200L/H (Canister Filter)

Total no. of goldfishes = 9 (each ~4cm or 1.5inch)

Thanks in advance.