I’ve had 3 rummy nose tetras in a 10 gallon tank for a little over a week and I’ve noticed they stay in the bottom right corner of my tank all the time besides feeding. Is there something wrong or are they just adjusting to the new tank?
Agree. First issue, they are likely still adjusting to a new environment. This is quite a sensitive species, we have had so many threads over the past years about new rummys dying. But having said that, other factors are important too, and one is the space and the number. This is a shoaling species and it needs a lot of them, I would never go below 12. I had 23 in my 70g for years. It is one of the most tightly shoaling tetras, and quite a sight as the larger group swim lengths, they are active. However, you need at minimum a 3-foot/90cm long tank; volume is not important (within reason obviously) but length to swim is important.
I think the picture is making them a lot more pale than they really are in person and I’ve been watching them for a while without standing right in front of them and they seem to be swimming around a lot more up and down the tank
My advice here is to help you understand and provide for the well-being of your fish. We all started out making mistakes, and we learned.
You need a group of 10-12 absolute minimum, just 3 or 4 or 5 will be seriously stressed. If you tank does not have enough room,then return these to the store and explain why you cannot keep them. There is no beating around the bush here...these fish have a need and it has to be fulfilled or they will not be in good health, and likely aggression to each other and other fish will result.
And GH (or hardness). Some fish need soft water, others need hard water and this seems to be more important for small fish suited to a 10 gallon tank. Your water provider's website should have this info, but if you are on a well you can take a sample of tap water to a fish store and ask them to test GH.
Is the tank the standard size for 10 gallons, 20.25 x 10.5 x 12.5 inches?