Chlorine remover is VERY important when it comes to taking care of fish. Freshwater Fish can not survive in untreated tapwater unless it has had over 24 hours to set.Red spots-entirely depending on the variety of your fish - may be caused by high ammonia.Ammonia when in high levels will actually burn fish and cause them to have red spots called burns.The burns(if the fish is put into clean ammonia free water) will turn black and then heal over in a couple of days.I'm not sure what type of fish you have (for some fish it is normal for them to have red spots) but I'm guessing that your fish are suffering from ammonia burns and need to be put into clean ammonia (and chlorine) free water.If you don't want to shock your fish from the extreme change in pH they would undergo if you did that I'd recomend doing plenty of small water changes of 10-25% in the next few days.
I think the best thing you can do is let the tank sit for three days ,full of water with the pump going. If you don't want to wait you should at least add some Chlorine remover before adding the fish. You can find Chlorine remover at any pet store. Just takes a few drops. I usually do both; add the Chlorine remover then let the tank sit a few days.
Water conditioner is for removing chlorine from tap water to make it safe for fish to live in because chlorine will kill fish. Bottled spring water does not have chlorine so why on earth would you consider using a chlorine remover? If it ain't there, you can't fix it hey?
Yes, chlorine is harmful to fish and can kill them if they are exposed to high levels of it in their water. It is important to always use a dechlorinator when setting up a new aquarium or performing water changes to make the water safe for fish.
If your talking about Swimming pool its because your pool has chlorine in it and chlorine kills fish :(
Look at "why has my fish got white spots?"
No fish can survive in a chlorine pool. Chlorine is a chemical disinfectant used in pools to kill bacteria and algae, but it is harmful to fish as it damages their gills and scales, leading to suffocation and death. Fish need clean, dechlorinated water to survive.
catfish have whiskers and spots
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Nothing is wrong with your fish. Orange spots are normal, but if you're worried, take it to the vet.
Your fish may have swum away or hidden in the tank. Look around the tank and check any hiding spots. You can also try using a net or gently moving decorations to locate your fish.
If it has white spots (tubilcles) on it's gill covers (cheeks) and along the front of it's Pectotral fins then it means it's a male fish :-)
If the fish is a Goldfish you check to see if the spots are only on the fishes gills and pectoral fins. If so the white spots are indicating that the fish is in breeding condition. If the white spots are visible on other parts of the fish then your fish probably has Ich/Ick/ Whitespot and you will have to use a commercially available cure normally available at the pet shop.