probably best that I stick to something a little bit easier to keep regarding bottom feeders. My tank on the other hand reads entirely negative for ammonia and nitrites. This cycling thing seems to have gone very well and very quickly for me - I take it that it doesn't normally go so quickly but I'm not knocking it!

I'll head down to my local pet store either later on today or tomorrow morning I think to see what they have available.

What other bottom feeders are available to me that live in warmer waters? I don't have a great deal of 'floor' space in my tank and I wouldn't want to overload my tank. I could try asking down at my LFS but they were the ones that suggested fish-in cycling to my brother so I'll ask around the net first and look into it a bit more. I'll leave out the focal fish I think and leave my tank slightly under-stocked so it's easier for me to manage.

I'll get the more active top-swimmers first, introducing them 2 at a time and 5 days apart until I have 5 or 6 in my tank.

My brother's gold Zebra Danios are still 'fighting'. One at the top of the tank, one at the bottom. I hope they sort out their differences when they're more of them. I heard that sometimes, the original two or three Danios that do argue, tend to isolate themselves from the school when more fish are introduced. I hope this isn't the case - the fish will be in an extended state of stress for a long while if it is (I imagine).

Also, yes - when I gave it a proper look, there is a large rectangular section on the back of my tank that is free of plastic from the hood. This'll be enough I take it? it's about 30-40cm long, along the top of the glass and about 15-20cm wide.

I'll take a look at AquaClear and Whisper filters as soon as I get the chance if this is enough space to accommodate a hang-on-back filter.

Sounds like the tank is going well . There are sometimes multiple nitrite spikes so keep testing nitrite just in case. Is there any nitrate yet? That tends to mean you're really close.

I don't remember if you mentioned it but can you get kuhli loaches locally? Those are pretty common in U.S. pet stores, at least. If not, see if they have any other loaches...there are a few that stay small . Another option would be to consider shrimp...a bunch of cherry shrimp would look nice and they're fun to watch. A single bristlenose pleco might be OK in a 15-gallon although they're kind of messy...might not make for a low-maintenance tank, ha.

Yeah, that's enough room for most HOB filters.

patience is key to starting up a tank with success.
My 12 gallon has been running for 2 1/2 months and I presently have only 5 silver Molly fish in it.
I started with 2 for a few weeks, then 1 more, then 2 more; carefully watching water levels and all is well.
Running an Aquaclear 30 hang on back filter which has adjustable flow.
Good Luck !