Hey Dude,
Unless you know what the fish has died from then I dont really know what to tell you. However, if the fish died from natural causes such as old age or water conditions its probably best to do a water change on the tank as dead fish release amonia ( or anything decaying for that matter) into the water which would be harmful to the others and the babies. Get rid of about 50% of the water but dont take the fish out while you do it. Make sure you use water conditioner and what not. One dead fish
SHOULDNT affect all the others UNLESS there is something wrong with the overall condition of the tank set up ie; too many nitrates etc. A good water change as mentioned should do the trick
Hope this helps,
Cheers,
Lauren
