Fish identification (WCMM?) and behavior help

[sugarkube]

Hello,

 

TL;DR

I was sold some fish at Petsmart that I was told were White Cloud Mountain Minnows, but they don’t look like the original minnows I got from the LFS and they’re acting aggressively to the other fish. Are they actually WCMMs or something else?

 

I kept Betta fish for a while over a decade ago and now that I’m settled in again I want to get back into the hobby. I went to my local fish store recently and they suggested I start my 6 gal tank with White Cloud Mountain Minnows. I asked if they could be kept in the same temperature as Bettas and he answered yes. Came home with 3 minnows and some plants and after I did quick reading, come to find out these fish are cool water fish, not tropical. Really annoyed me but whatever. Just didn’t use a heater with them and the water temp is holding at 72. Within 2 days the largest one died. So I had 2 left, brought the dead one back to the LFS with some of the aquarium water because I wanted a new fish. They tested the water and everything was fine except for 0.25 ppm Ammonia. They wouldn’t give me a new fish because they claimed that’s what killed it (even though the others were fine). I didn’t want my other fish to get stressed out so I went to Petsmart and bought 2 more.

I took them home and I’m realizing they don’t even look the same. They’ve been swimming aggressively at the other fish in the tank and now the 2 original WCMM are getting stressed out and floating at the top of the water.

What’s going on here? Do I actually have 2 incompatible fish species? I’m getting driftwood ready as we speak (been boiling wood for 2 days trying to get the tannins out) so that the tank has more hiding places but I was told these fish are very peaceful.

Thanks for any help!

[CJs Aquatics]

Can’t help much with the identification that’s not my species of expertise, however as far as aggression, you can do a few things, craft mesh divider or something similar is an option but what I typically do is remove the fish  from the tank, then re introduce them at the same time, or perhaps move things in the tank around so there are less disputes, if that doesn’t work after a time putting the aggressor in time out generally does 

[BlueLineAquaticsSC]

Looks like a tetra to me, maybe a glow line tetra

The LFS one is definitely a WCMM

[RockMongler]

It's a glowlight tetra.  Petsmart keeps them in the same tank as their WCMM at the stores I've been to.  I actually had the same problem once; wanted WCMM, got glowlight tetra, because they look rather similar at a casual glance especially when they aren't colored up at the store because of stress and whatnot.

[Colu]

I second glow light tetra