The non-eating one is probably sick, posibly with internal parasites or a bacteria infection, can you fill out the info below;
Size of aquarium/pond -
Aqua one 510 80L
Types of fish -
1 Betta, 11 Cardinal Tetras, 2 YoYo loaches
Number of fish and sizes -
Tetras vary, betta is healthy normal size and so is one of my loaches
Filtration used and how do you clean it and how often -
Stock filtration with the 510, ceramic noodels, sponge etc, cleaned it prob twice in 5 months in the old/used water from my water change
How much in the way of water changes and how often --
Roughly 25% evey few weeks
Do you dechlorinate -
Yes evey water change
Symptoms of sick fish ie, spots, behaviour, etc -
Non that i have seen beside not eating still swims around happily, holds its own with other fish acts the same as my larger one
How long has the fish been sick and which medications are your currently using or recently used -
Could really tell hasn't really eaten like the other one since i bought them approx month ago, haven't tried or used any medications
Test results for ammonia, nitrite, nitrate and ph both from the tap and tank -
i don't have specifics but the Ammonia and NitrAte are zero and ph is a tad on the high level
Anything else you need us to know -
In particular, is the non-eating loaches barbels/whiskers eroded looking at all? Does the loach appear underweight/have a sunken looking stomach? The below thread may be of help to you, internal parasites are not uncommon in loaches;
I haven't checked its barbels/whiskers but still digs around well enough, yes looks a little skinny but just looks immature same as when purchased
http/www.fishforums.net/index.php?showto...ernal++parasite
This is what healthy Pakistani loaches should look like;
http/www.loaches.com/species-index/botia-almorhae