Ok sorry maybe I did come on a little harsh
As much as there are people attacking people that's as a result of people who, and I don't mean you, come here asking for advice then ignore everything and declare they've kept three great white sharks and two puppies in their 20G tank for X months and everything is fine.
The reality of your situation is the silver tip shark is a bala shark and they not only require over 150G (Some say 200-300G) tanks but they also require schools or they get very neurotic so it really does need to be rehomed.
Rainbow sharks are ok community fish but they require 40G minimum and even then you should only keep one because as they get older they get incredibly territorial. If you are adamant you are keeping a rainbow shark rehome one and be aware in a year or so it could well kill your entire tank with the exception of the bristlenose if it feels like it (And it most likely will).
Barbs are notoriously nippy fish and they do not go well with the long tails of guppies, in such a small tank I would say it's likely a death sentence for the guppies long term.
Two gouramis in such a small tank is also a concern as they are also territorial with each other and the lack of space will likely lead to one dying of stress, others have had success however but they are the exception as opposed to the rule.
Here's a link to a site called aqadvisor (
AqAdvisor - Intelligent Freshwater Tropical Fish Aquarium Stocking Calculator and Aquarium Tank/Filter Advisor) which, while not perfect, is a really good tool for beginnings to learn to get their stocking in order before they begin pushing boundaries.
Don't feel bad your current stocking really isn't compatible, my first stocking was way worse than yours and I ended up rehoming 90% of my stock thanks to the poor advice my LFS gave me.
Apologies again if I came on too harsh
