If only it was that simple .......
IMHO Andyroo has come the closest in understanding the what, and how it would take to pull this off. To which I would perhaps add a large whack of Ketapang or similar leaves (dry oak, birch, beech), just to give some earthy substance to the substrate. They also add shelter for smaller fish and/or fry, and add extra tannins to the water.
running on pure assumption:
Spawning seems to be associated with rain and/or rainy seasons, thus flooding. So set up a 1000Gal pond in your garage and set 5x Koralia #3s in a bundle along one edge shooting along one wall. Now plumb your roof gutters into the pond, probably with some sort of ball-valve so you can say yes or no. Put in 200Lbs of pool-filter sand, 500x ramshorn and 500x MTS and 100x mystery snails plus 30x small tetras, 50 cherry shrimp and some grassy plants. Now put in 20x 1' segments of 1 & 1.5" PVC pipe or bamboo. Rig up a big filter. Wait 6 weeks for it all to fester & bubble (toil and trouble etc....) then put your loaches in...
Let the ecosystem deal with water quality ('cept for top-ups) and use the rainwater for changes- so get an overflow to let extra out. Might want to wait for summer for that part...
Acid rain can be pH 4 & 5, so move closer to the oil-sands
, and Bob's yer uncle.
For those that haven't already read the following section on breeding, this is worth a read.
http://www.seriouslyfish.com/profile.php?genus=Chromobotia&species=macracanthus&id=349
While the following article doesn't involve clown loaches, it describes the whys, what's, and how's of river fish, and how seasonal shifts & rainy seasons trigger spawning of fish such as clown loaches. This will answer most of the questions that some of you are seeking.
http://www.fao.org/docrep/003/T0537E/T0537E06.htm
SEASONALITY OF FEEDING
In temperate rivers and streams the onset of winter usually marks a drop in overall productivity of aquatic system and in the production of food organisms. Furthermore, the amount of food eaten by fishes is closely related to temperature thus a general cessation of feeding occurs in most temperate and arctic species during the winter months. In tropical waters the effects of temperature are clearly less pronounced but since Chevey and Le Poulain (1940) remarked on the fact that fish did not feed in the Mekong system during the dry season it has become generally accepted that feeding by fish in tropical rivers is likewise highly seasonal all over the world. In flood rivers the feeding cycle is clearly linked to two factors, firstly the food supply and secondly the population density. During the flood the rapid increase in food organisms, together with the wide dispersal of fish over an extensive biotope, favours intensive feeding. At low water, when the aquatic environment is contracted the fish are concentrated in a few permanent reserves of water and food sources are limited or exhausted, fasting therefore ensues. In the tropics this contrasts with the more or less continuous feeding of fish in lakes; although in some species inhabiting rivers closely allied to lakes such as the Lake Chad/Yaeres system the fish cease feeding at low water despite the adequate supply of food which would enable them to continue feeding at all times of year. In reaches of Indian rivers having little or no floodplain the seasonality of feeding may be reversed with more intense food intake during the dry season. Bhatnagar and Karamchandani (1970) attributed this to the food being washed away by the high current during the flood in the case of Labeo fimbriatus. Tor tor showed a similar pattern to L. fimbriatus although in this case Desai (1970) correlated the lessened feeding with breeding. It would seem that feeding stops just before and during breeding in flood and reservoir rivers alike. There are nevertheless seasonal differences in the availability of food which depend on the morphology of the river.
The intensive feeding by fish during the periods of abundance permits them to build up large stores of fat which are sufficient, not only to tide the animals through the following barren winter or dry season, but to elaborate gonadial tissue in preparation for breeding.
TIMING
Reproduction of fish in rivers tends to be highly seasonal throughout the world. This seasonality appears correlated primarily with two factors, temperature and flow, which in the temperature zones are more or less synchronous in that increases in flow result directly from the snow melt and increased precipitation associated with rising temperatures in spring. Approaching the tropics the influence of temperatures seemingly diminishes and the flood regime becomes increasingly important as the major regulator of breeding. Thus throughout the world the onset of reproduction of the majority of fish species tends to coincide with the earlier parts of the flood.
Some additional background on this geographical location.
http://www.wetlands.org/RSIS/_COP9Directory/Directory/2ID002.html
IMHO the pH factor isn't nearly as important as some here may feel.
It's definitely part of the equation, but there's much much more involved than simply tweaking the pH, and with regards to the biotope where clown loaches are found, there wouldn't be any
sudden shifts in pH.
Many species of fish from this area such as
Scleropages legendrei (Super Red Arowana) Betta sp, etc are bred & raised commercially on farms in Singapore where the local pH varies from 7.2-7.9. In the wild some of the small ponds & ditches where betta are collected can be as low as pH 3.5, yet they have been successfully bred in much higher pH for many years.
The rainy season brings cooler water temps (not warmer) and raises the pH in the peat bog areas. Perhaps not by a whole lot, but 8-12 metres of rainfall is certainly not going to lower it in areas that are already sitting at a pH of 4, or less. The fry have a much greater survival rate in this area due to the abundance & variety of food stuffs available during the rainy season, and the low density of predators compared to what is found in the main rivers. The shear size of the floodplain tends to thin the predator density out drastically. Their biggest predator at this time of the year is probably fisherman.
I spent most of my formative years growing up on a large river system that flowed into one of the Great Lakes, and every spring watched one species of fish after another make their annual spring spawning run.
The triggers, longer days (more light), a change in water temp, and most importantly, an abundance of food that allowed the females to come into spawning condition.
Not to rain on anyones parade, but IMO if you aren't prepared to set up a system along the lines of what Andyroo suggested earlier on in this discussion, I personally don't think that you have a hope in hell of pulling this off.
I would love nothing more than for someone to prove me wrong.
