There arent that many books out there with any in depth information regarding loaches so I thought it would be a good idea to create a list some of the books that do contain loach info.
Revision of the Torrent Loaches of Borneo (Balitoridae: Gastromyzon, Neogastromyzon), by Tan Heok Hui, 245 pages containing photos, maps & drawings.
By Maurice Kottelat, 262 pages, 180 b/w photos, figs & maps, 33 tabs.
A revision of nemecheiline loaches (Pisces: Cypriniformes) of Thailand, Burma, Laos, Cambodia and southern Vietnam.
by Tyson R. Roberts (1989). California Academy of Sciences. 210 pp., b/w photos, illus, tabs, maps.
By I-Shiung & Chang, Yung-Ching Chen, 284 pages, colour photos and B/W illustrations.
A whole lot more than just Loaches and a great read for anyone interested in fishes from this region or planning a biotope setup.
By Maurice Kottelat, 198 pages, 481 Col photos, b/w illus.
More than just loaches but the loach info alone makes this a must have, this is a superb photographic guide to Laotian fishes. All species known to date are illustrated by colour photographs and data on the distribution and habitats of these species is included.
By Maurice Kottelat and J Freyhof, 646 pages, 600 photos, illus, dist maps.
This reference work covering 546 native and 33 introduced species is a very important contribution on the biodiversity of freshwater fish species in Europe. Much of the information presented is drawn from original research conducted over 8 years in 24 European countries. Again this book contains more than just loaches but the information about European loach species is probably the most concise available.