Sick G.T. hes got blury-ish eyes n doesnt swim a lot

Question
hi im jp n this is my 1st time for this really, so hope u get this. i have a 5" G.T. in a 24" tank that previously had a "Pangasius sanitwongsei" tepa fish in thai. i'm in thailand by the way. 2 weeks ago, the tank conditions got really bad cuz i didnt have time 2change d water(i know i'm really sorry man..) n the weather sort of changed hard core out of no where. finally got to change d water last week. n d next day i found my G.T. just lying on the bottom floor n my tepa had a really rough shin to it like white spots all over, so i droped a cap of malagreen already. a day later i decided 2get a heater. i come home n my tepa's dead. now the heater's been plugged @ 30c. for the past 3-4days. the G.T. is swimming now but still dont look wright. 2 days ago i've noticed that there's sumthing in its eyes. like fish's eyes are suppose to be clear n shinny right? but not his, its sort of blury-ish with sumthin in the middle. i've taken out the heater already just now. help pls help help. would appreaciate any advice givven thanxs a lot sorry its quite long.

Answer
Hi,
I'm a little confused. Did you say your tepa died and then was alive again? or am I just reading your question wrong?

The 1 thing that would do that is shock from the cold. I believe heaters are a must have no matter where you live. For example, Thailand is warm and the perfect climate, but here it's -32C with 50 mile per hour winds.

So, in the future:
1.)Have a heater
2.)Get a good filter so that the water doesn't deteriorate again
3.)Keep in mind cichlids have a good immune system. He should heal by himself in clean water if he's still alive.