Not quite a beginner but looking for some suggestions

[The_eris]

I've been keeping fish since I was around 8 years old but my dad has been keeping fish my whole life and I have grown to love fishkeeping. I am looking for suggestions on what fish to get next

I have a 20-25 litre tank with live plants and wood, plenty places for fish to hide if need be. I have kept various fish in the past most recently serpae tetras and kribensis however after a feeding accident while on I was on holiday all but 1 serpae and 1 kribensis have died.

What fish would you recommend for keeping next? I was thinking something along the lines of Glowlight tetras or White cloud minnows?

 

[Colin_T]

What are the tank dimensions (length x width x height)?

What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

 

[The_eris]

I use RO water but just checked the pH GH and KH they are around 6.6, 4°d and 3°d it is 15(w)x40(l)x30(h) with a bowed front

 

[Essjay]

25 litres is a very small tank and is suitable for only a very few fish. With soft water the realistic options are a single betta or a shoal of at least 12 of one of the Boraras species. The best known of these is chili rasboras (Boraras brigittae) but there are several others as well.
https://www.seriouslyfish.com/species/search/boraras.
The other option for 25 litres is shrimps.

The vast majority of fish need a minimum tank length of 60 cm for the smallest fish with many species needing a lot bigger than that.
Of the species you mention, both glowlight tetras and white clouds need a minimum of 60 cm.
Serpae tetras (nasty nippy things) need at least 80 cm and kribs at least 60 cm so neither were suitable for this tank I'm afraid.