I regularly test my water for KH, GH, PH, NH3, NO2 & NO3. Is there any other tests that you would recommend? Not just for the benefit of the fish, my plants too.
As Colin said, these are the pertinent tests. Once a tank is cycled and becoming/becomes established, ammonia and nitrite should not be necessary except at the first sign of a likely problem. GH and KH should not be necessary unless you are specifically targeting these within the tank; targeting means adding something deliberately to alter GH/KH, such as calcareous substrate/rock which will increase GH/KH (and pH). Otherwise, once you know the GH/KH of the source water, you can expect it to remain close to that unless of course the source water itself is liable to fluctuate due to the initial source.
Nitrate and pH are tests that can be done periodically, and again at the first sign of trouble. Both of these can change, and the aim is to have them stable. These are the only tests I ever do on tank water on any sort of periodic/regular basis, but even these are very infrequent now since my tanks have been stable for many years.
You do want to always test the source water on its own for all of the mentioned aspects (GH, KH, pH, ammonia, nitrite, nitrate) to determine if any are present so you know what action may be required. Nitrate in the source water for example is an issue and may need to be dealt with before the water even enters the fish tank, depending.
As you mention plants, the GH is important there. I have zero GH in my source water, so calcium and magnesium (the minerals responsible for GH) have to be added for the plants. My soft water fish species do not need this at all in the water.
Could you please recommend some fish that would be more suitable? My favourite fish are the Julii Corydoras, native to Eastern Brazil. I would really like to try to recreate their natural habitat including the other species of fish.
You mentioned conflicting information and sources for reliable information, and this is certainly an issue in this hobby (the conflicting and erroneous information). The Baensch & Riehl Aquarium Atlas book is probably the best in the book line, I have the first three volumes. The only problem is that they are getting "old" now and some species information does change.
For online reliable and accurate species data, including habitat, parameters, etc,
Seriously Fish is tops.
The true
Corydoras julii occurs in a few coastal rivers and certain areas in the lower Amazon basin, Brazil. It is found in small creeks, flooded forest, sandy pools. This is one of four very similarly-patterned cories that are frequently confused and will often be seen in stores under incorrect names.
Corydoras julii, C. leopardus, C. punctatus and
C. trilineatus all share a large black blotch in the dorsal fin, a barred caudal fin, and a horizontal stripe along the body at the juncture of the dorsal and ventral lateral plates; the body is spotted. However, all these species are highly variable in their pattern, and the horizontal stripe may be absent in
C. julii.
The subject species is quite rare in the hobby, since it occurs in rivers and areas that are generally not heavily-fished commercially and is therefore seldom exported; the few times it does appear it has probably been collected in the Rio Para which is regularly fished. The "Julii" cory most often seen in stores is more likely to be
C. trilineatus. The true
C. julii has a spotted pattern on the head and body, and the lateral stripe is either not present or extends only midway along the body.
C. julii is also somewhat smaller and more compact-looking in size than
C. trilineatus.
The photos on Seriously Fish for these two species entries will illustrate the differences. Whichever, maintenance and habitat is identical.
I would have to do some digging to find the sympatric species if you want to be absolutely authentic. But generally, most of the characins will be suitable as far as parameters and habitat. The tank size will obviously limit many, and all will need a group as they are shoaling.
