[Lupin]

I wouldn't stick to the clown loach as a good fish for 75 liters.
Swordtails are too big for a 75 liters and will need a cover glass as they are good jumpers. You may stick instead with platies.
As for tetras, don't buy them if your tank hasn't established for 3 months or more. They are rather sensitive to extreme changes in water chemistry. However, you may try the Black Skirt, Lemon and Beacon tetras.

 

[Lupin]

Ok. Just wanting to make it clear that some fish can't fit in a 75 liter tank.

 

[Lupin]

Hi Oceane,
In general, RTBS are aggressive. However, some fish can be unique even if in general, they are what they are created to be.

I skim read again and found out no one(well, even me, as I didn't noticed that) has advised against the kissing gouramis and silver dollars. Those fish are rather too large for a 20 gallons tank. Silver dollars kept in a shoal of 6 need a tank minimum of 70 gallons. For kissing gourami, a pair has to be housed in a 55 gallons minimum.

 

[Lupin]

Arent rummy nose tetras a bit harder to care for? Dont they require a certain PH or something?

They do not require certain pH at all but these fish can be quite sensitive to ammonia, nitrites and nitrates. These fish are also likely to be stressed and mortality rate during transport is often high however once they are acclimated, these fish can be very hardy and will live very long.