Tin foil barbs, silver sharks (bala sharks) and oscars grow to about 1 foot long and can usually reach this size in 12-18 months. The tin foils and silver sharks should be kept in groups of 6 or more. However, the tank isn't really big enough for a group of each.
Your silver sharks are really skinny and not looking good.
The silver dollars need plant matter in their diet. the tin foils would enjoy some plant matter too.
The striped loach on the bottom of the tank is a Botia lohachata (yoyo loach). They do best in groups of at least 6 (preferably 10) or more. They tend to be nocturnal but in a well planted tank or a tank with lots of hiding places, they will come out during the day. They normally grow to about 5-6 inches but a friend of mine had some that grew to 8-10 inches in 12 months.
The roseline barbs (torpedo or Denison barb) do best in groups of 6 or more.
I can't think of the little brown cichlid but
@Wills should know. Hopefully he can take a look and ID it for you.
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I would probably rehome the silver sharks and get a few more roseline barbs and loaches. Maybe look into rehoming the tin foil barbs and or silver dollars too or keep them and see how they go.
Do a bigger water change and do it every week. Cichlids can have problems with hole in the head disease if kept in dirty tanks. Your cichlids look fine now but you want to do more frequent water changes to keep them healthy. I recommend doing a 75% water change and gravel cleaning the substrate every week. You can do a 50% water change each week if you are concerned. You have sand on the bottom so you can gravel clean or hoover over the top each week and stir it up or gravel clean it monthly if you like.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Cleaning your filter in a bucket of tank water once a month is great. Keep doing that.
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