First on fish identification, the fish in the photo in post #4 is not a Flying Fox. The fins on the Flying Fox are black or reddish hue, edged with white; those on the fish pictured are all clear. I think the pictured fish is a Siamese Algae Eater (common name). This fish and another commonly called the False Siamese Algae Eater are identical except for the position where the dark lateral band ends; on the False SAE the dark lateral band ends at the caudal peduncle whereas on the SAE this band continues into the caudal fin. The photo here stops just into the tail (caudal) fin and seems to show the line extending onto the fin, so it is a SAE. These species, and a couple others, are frequently mis-labelled in stores; always verify the species before acquisition, as they have differing temperaments.
The scientific name of the true SAE is also confusing. Those not interested can skip this para, but in case anyone is interested, I'll explain. The common name Siamese Algae Eater is regularly applied to several related but distinct species. The species Crossocheilus langei is the one most often encountered in the hobby as the Siamese Algae Eater [SAE] and is the best at eating black brush [aka red beard] algae. The "true" SAE is actually Crossocheilus siamensis, a species initially described by H.M. Smith in 1931 as Epalzeorhynchus siamensis and moved by Banarescu into the genus Crossocheilus in 1986, and which has probably never been seen by hobbyists since the holotype [the specimen collected and used for the description] is the only one known. To further confuse, the fish described as C. siamensis by Smith was subsequently determined to be conspecific with a prior described species, Crossocheilus oblongus, so in fact there never was a C. siamensis as a distinct species, and the name now is a synonym for C. oblongus.
You have some issues here. The SAE is not a small fish, attaining 6 inches. It should be in a group, but some keep it as a solitary specimen (you have two, that's a problem). It should have a larger tank, so frankly I would return them (the injured one may not make it, and the store probably won't want it).
Clown loaches get much larger still, 8-12 inches, and absolutely must be in a group of five or more, sometimes four can work but it is not the best. This fish is highly social and alone or in less than 4/5 will develop serious stress and hierarchial problems. It definitely should be returned, it is not going to be healthy guaranteed.
The aquarium is seriously overstocked now, and water changes must be much more frequent that every few weeks. A change of 50-60% of the tank volume should be done once every week. With the removal of the loaches and SAE, and sorting out the other small fish ("zebra", "tetra", penguin tetra) things could work.
Byron.
