so i bought my two gerbils from pets at home around 7months ago and they went from a small tank in pets at home to a descent size gerbirallium with lots of things to do. They have been perfectly fine getting along for the past 7months however one of the gerbils dexter used to nip me alot but never enough to draw blood however he had never done it to oskvr before. around 2 days ago i noticed my gerbils were making ALOT of noise then usual with the cage banging etc.... so i looked at them and dexter kept going up to oskvr who was in the corner of a shelve in their house hiding and pushing dexter out and they kept squeaking. after they squeak at each other for about 20seconds oskvr will make a run for it and dexter would chase him everywhere at his tail I never saw them sleep for the past 2 days or hide and usually they always are since they have many hiding spots I went out today 4hours prior to the incident and oskvr was perfectly fine, no blood or anything but the same chasing which i thought was play fighting that i read on google. i took everything out the cage apart from this coconut den they like and the food and water and a hiding spot the night before to try get them to stop fighting and sleep together. i come home from shopping after leaving them for 4hours and i find oskvr eyes closed in the corner of the tank still breathing with the whloe bottom half of him bitten and covered in blood. straight away i take him downstairs and treat him with sterile water and some cream. i wrap him up in a blanket and place him on a heated blanket and he keeps trying to move every minuets for about 5seconds. i leave him be for around 20 minuets to see if he will come around and maybe hes unconscious from the shock and his tale shaked for around 5 seconds and his mouth kept opening and closing then he stopped breathing and it was heart breaking. i went upstairs and dexter was acting like nothing happened and is acting like he doesent even know. What do i do with dexter (the one alive) do i put him up for adoption since i cant even befriend him? or was it not even him who killed him as an attack was it because of an illness oskvr had? if so do i get him another friend? also as much as i dislike him right now how do i keep from getting lonely? thankyou p.s sorry for any spelling mistakes i rushed this!