Good choice for hard, alkaline water, as they come from limestone lined caves in Mexico. They also appreciate a cool temperature (~20C) over the winter months and so could be kept in an indoor heaterless tank without issues.
I kept 16 or so in my outdoor pond for the warmer months, well actually right up until Nov. I think the nigth time temp. was around 0C to -3C. They all did really good, all fat from eating endless supply of larve during the summer.
I love these fish and have kept them for years. The only time I had trouble with them was when I had a male betta in the same tank. I never saw them nip the betta, but he was terribly frightened of them. I finally moved him out to save him the stress. I keep them in an unheated tank with corydoras, livebearers, yoyo loaches, and bristlenose plecos.
Blind cave fish are basically peaceful but since they cannot see, they tend try to sample everything they come in contact with. They are not persistant and once they realize they have not found food, they are right on their way again.
Thanks guys really helpful stuff, I think my work can order them in but I'm not sure, but anyways I'm along way off getting them yet- need to upgrade my tetra tank first xx