The danios tetras and barbs need to be in groups of at least 6.
However, I assume the tank is around 100 cm long? Torpedo barbs need a tank at least 120 cm long which is unlikely with a 180 litre tank so I would rehome those rather than get more. Kissing gourami are big fish and need an even bigger tank - at least 150 cm long, so I would rehome those as well.
That would leave the shark, danios and tetras. You could then increase the shoals to 10 or even 15 of each. You don't mention which species of tetras you have, but unless they are one of the larger species, that number is OK in 180 litres.