Lots to comment on here, starting with the differing information on this and most other species. There is only one way to know what sort of environment we need to provide (as closely as possible) for the fish we maintain in an aquarium, and that is by researching the natural habitat. Each species of freshwater fish has evolved over thousands of years to function in a very specific environment, which includes water parameters (GH, pH and temperature), the natural materials (substrate, wood, rocks, plants), water flow, and light. The fish "expects" these, they are programmed into the DNA of the species. Most species are narrowly demanding in this regard, but some have more tolerance; but this tolerance is solely because of the species' biological makeup. In other words, there are natural reasons that species "x" is less restrictive than species "y".
If we want our fish to be healthy, we have no choice but to understand their requirements and provide accordingly. It need not always be strictly natural, it can be artificially representative. But the fish must have an aquarium environment that replicates or simulates their habitat. Always. There are no exceptions. Even generations of commercially tank-raising fish cannot change the basic DNA of the species.
"Happy" fish is something we cannot ever know because we cannot talk to the fish to ask them. People sometimes assume the fish are "happy" because they are swimming around, eating, even spawning. But this is a false assumption. Fish like all animals have a strong inherent will to live, and when faced with adverse conditions they will do everything they can to somehow manage or overcome them, until the stress weakens them and they succumb to disease or just die. The only way we can even begin to presume the fish are "happy" is when we strictly provide what they expect in their environment.
Prior to the internet, published books and periodicals were the basis of our source of information, and they were more often correct (subject to the advances made in scientific understanding and data) than not. The internet has certainly been a positive factor in our lives, but it can also be a terrible hindrance. Anyone can post videos and promote utter nonsense. The only way to weed out this misleading data is to know the individual behind the data. There are sites owned and run by trained and knowledgeable biologists, microbiologists, and ichthyologists, or by those who have studied under such individuals. Seriously Fish, Corydoras World, Loaches Onlline, Planet Catfish are just four of the reliable sites that come to mind. This is a scientific hobby from start to finish; we are keeping living creatures in a natural aquatic environment that is governed solely by the laws of nature and science. Once we understand that and work with the science, we will have success--and the assurance that our fish are being provided with the best environment we can give them.
To the Reticulated Hillstream Loach. Assuming this to be the species
Sewellia lineolata [always search for info with the scientific name of the species] this describes the habitat:
Restricted to shallow, fast-flowing, highly-oxygenated headwaters and tributaries characterised by stretches of riffles and runs broken up by pools or cascades in some cases. Substrates are normally composed of bedrock, sand and gravel with jumbles of boulders, and while riparian vegetation is often well-developed aquatic plants are typically absent. The most favourable habitats contain clear, oxygen-saturated water which, allied with the sun, facilitates the development of a rich biofilm carpeting submerged surfaces. During periods of high rainfall some streams may be temporarily turbid due to suspended material dislodged by increased (sometimes torrential) flow rate and water depth. At one locality in the upper Thu Bon this species was collected from a very fast-moving (> 1 m per second) stretch of river around 80 m wide and containing turbid water. There was a series of rock-filled rapids and deep pools with a sandy substrate, and the fish were also collected in marginal rocky pools unconnected to the main river.
The foregoing is cited from Seriously Fish. Keeping this habitat in mind, they suggest the aquarium be as follows:
The water must be clean, well-oxygenated, and ideally turn over 15-20 times per hour so we suggest the use of an over-sized filter as a minimum requirement plus additional powerheads, airstones, etc., as necessary. Aged driftwood can also be used but avoid new pieces since these usually leach tannins that discolour the water and reduce the effectiveness of artificial lighting, an unwanted side-effect since the latter should be strong to promote the growth of algae and associated microorganisms. Exposed filter sponges will also be grazed, and some enthusiasts maintain an open filter in the tank specifically to provide an additional food source. Although rarely a feature of the natural habitat aquatic plants can be used with adaptable genera such as Microsorum, Crinum and Anubias spp. likely to fare best. The latter are particularly useful as their leaves tend to attract algal growth and provide additional cover. Since it needs stable water conditions and feeds on biofilm this species should never be added to a biologically immature set-up, and a tightly-fitting cover is necessary since it can literally climb glass. While regular partial water changes are essential aufwuchs can be allowed to grow on all surfaces except perhaps the viewing pane.
Water parameters are:
Temperature: Can tolerate higher temperatures provided its oxygen requirements are maintained but for general aquarium care a value of 20-24C is recommended.
pH: 6.0 to 7.5
Hardness: 18-179 ppm
www.seriouslyfish.com
