No, this is a myth. Fish come in a variety of different shapes and sizes and the best practice is to give your fish ample space to swim from end to end. 

We recommend 1 Litre of water in the aquarium = 1cm of fish (without including the tail)Litre of water in the aquarium = Length(cm) x Width(cm) x Height(cm) / 1000

The best practice is to feed once to twice daily. feed no more than the fish will consume completely in five to ten minutes.

if you put in the right amount of fish. you should do at most once a week water change. You should do 30 - 50% water change per session

You should wash your filter once a week and change the wool cartridge once a month. (we sell the cartridge)

You should check your furniture if it is able to withstand the weight also the top if it is made of sturdy material. The top should not bend when heavy items are put on the top.
A small aquarium can easily weight 20kg

A constant 5 - 8 hours of light is enough for the fishes and plants. Long hours of lights will promote unslightly algae to grow

Algae usually grow because of high waste level in the aquarium and strong intensity/ long hours of lighting. Reducing the lighting intensity or duration will slow down the growth of algae. To stop and prevent algae from growing, Water change and cleaning of filters should be done and add algae remove solutions.

With proper cleaning, some are able to use, but it will be better if you get your rock from a fish store.

Water cloudy occur because you have a overload of waste in the aquarium
1. Usually because you overcrowded your aquarium with fishes.

2. You just started your aquarium and already introduced 100% capacity of fishes into the aquarium. One should only add in 30% of the capacity of fishes into the aquarium at one time. Introduce on the timeline of  3rd days, 14st day, 28nd days.

3. You just change a brand new filtration system and you did not use your old filter media but a brand new filter media. This will take out all the beneficial bacteria in the aquarium which are there to help to break down waste in the aquarium.

4. You wash your filter system with tap water instead of aquarium water. The chlorine in the tap water will kill all the beneficial bacteria in the filter media that should be there to help to break down the waste in the aquarium.

The safest for an aquarium to cycle before adding fish is 21 days.
But we tell our customer to add some fishes on the 3rd - 5th day to increase the efficiency of cycling the aquarium

A constant temperature of +- 1 is more important. Fluctuating temperatures cause more harm to the fish. For the recommended temperature for tropical fish is 25degree - 29 degree

Place the fish bag on the surface of the aquarium for 30min. then scoop the fish out from the bag with a net and introduce the fish into the aquarium gently. Throw the bag of water away. 

Go for The largest you can afford to get. large tanks are often easier to maintain than small tanks. You are allow to make more mistake for big tank compare to smaller one

1. Reduce your light hours to 2 - 4 hours per day to prevent algae outbreak.
2. Get carbon media to put in filter, they will help to absorb excess waste in the aquarium
3. Get Holiday Food for your fish from fish store.