Silver Sharks...

[jayjay]

Still not big enough, they are shoaling fish so need groups, the 8 came from Andy's 8.

 

[CFC]

The profiles give a 75g tank as a bare minimum for keeping balas in, as with any large fish a bigger tank is better but if someone finds themselves in possesion of some balas and is limited for space then a 48x20x20 would suffice. Most balas only reach around 10-12" in captivity, larger specimins do occure but are rare, the basic formula for the keeping of larger fish is to allow 4XL x 1.5W x 1.5H so a 12 inch fish requires a minimum of a 48x18x18 inch tank.

A 180 litre tank is no where near large enough, take it up to 300 litres and your in the right ball park, as the others have said larger would be better.