Hi there I am fairly new to fish keeping but certainly felt like I had things under control. Just to let you know, I am well aware that I have a small tank but am upgrading to a 20g once I move house at the beginning of August, so this set up is only temporary. I currently have a 5.5g tank, it is fully cycled as I let it run for approx 2 months before getting fish (0 ammonia 0 nitrite approx 5-10ppm nitrate) I currently have 3 guppies in there (2 female 1 male) which i've had for 2 weeks temperature approx 25 celsius (77 fahreheit) 7.4ph filtered with two javaferns also. I decided to purchase 2 bristlenose's yesterday afternoon. They were approx 2-3cm, so very little. Let them sit in their bag in the water for approx 30 mins. Then let them swim out, and they were having a ball. Swimming all over the tank, sucking on all the glass, guppies weren't bothering them all. I was watching them most of the afternoon. About 3 hours later, I noticed 1 of them on the ground not really moving, and one of the guppies pecked at him. No response. I poked him, no response. He had died. Shocked! The other one (which was slightly bigger) was hanging around the filter. Still alive, not exploring the tank at all, just staying put. I was worried. Woke up this morning, he has also died. I am not sure what has gone wrong, are bristlenoses more sensitive to changing water conditions? Should I have put some of my tank water in their bag with them, move putting them in the tank? I understand i have a small tank, but i cant imagine this is why they died. Or is the stress of being in a small tank with guppies? I am so lost. They were only going to be in there for another 4 weeks until being moved to a bigger. They were very little! Any help is much appreciated... thank you.