Stocking A 40g Breeder

I know that in the USA tanks come in different shapes for the same volume. Am I correct in thinking that breeder tanks are longer than usual and shallower?

So before I go any further can you tell me what the length, width and depth of this 40 gall breeder tank are please?

I see it is a shallower tank. I had an idea that breeder tanks were.

OK, next question. What is the pH of your water and what is the hardness? If you don't have a tester for hardness, the company that supplies your water should have that information on its website. I would hate to suggest soft water fish if you have very hard water, or the other way round.

The problem with those fish is that you have some that like soft water and some that like hard.

OK, I know you probably don't notice such things (teenagers usually don't  ) but have you ever noticed or heard your parents complaining about limescale in places like the shower head or a kettle? In other words, have you noticed white deposits round the holes in the shower head, or your parents having to clean it often? That is a sign of hard water.



I assume you are looking for something different from the fish you've already got?
You've said that cories are on your 'must have' list. In that case I would not get any more bottom dwelling fish, that area will be full with the cories. And fish like apistogrammas or kribs would pick on the cories if they spawned.
If you like gouramis, a trio (1 male 2 female) of honey gouramis would go nicely.
A shoal of pencil fish? Beckford's pencilfish, also called golden pencilfish, are the commonest and hardiest of pencilfish, provided your water is softish.

Or instead of those two, cherry barb are a nice colourful fish or maybe 5 band barb (make sure they are 5 band not the similar tiger barbs)
Or dwarf rainbowfish.



Just a few suggestions.

It depends on exactly how hard your water is. For example, there are some regions of the UK where the water is so hard I've heard fishkeepers call it liquid rock rather than water. They couldn't keep cories. But if your water is moderately hard there should be no problem and you could even keep a number of so-called soft water fish.

There are quite a few fish that can be kept in hard water, you would just need to avoid fish like rams, some tetras and things like most of the apistogrammas (though cockatoo cichlids would be fine in moderately hard).
Most of the rainbowfish like hard water, and I include fish like the blue eye group as rainbows.

When you get your tank, have a look at the fish and make a note of the ones you like the look of. Some of them won't be suitable but we can work out a list from the ones you do like.

There are a lot of units hardness could be in - like miles and kilometers - but I think the strips use ppm calcium carbonate. Can you look at yours and see if I'm right.
If I am right about the unit, 75 to 150ppm is in the range moderately soft to slightly hard. You should be able to keep the majority of fish, you just need to avoid Rift Lake cichlids which need it very hard and a few Amazonian fish which need it very soft.

Cories are definitely do-able.