SOS my angelfish are dying after a water change

[HollyJo]

Thursday evening I completed a 60% water Change on my 48 gallon tank. While filling the tank the heater bounced off the glass in the back corner of the tank and broke. I took the heater and glass out and threw them in the garbage. I replaced the heater the next day with one from Walmart. I have it set for 80 degrees. Now 1.5 days later my fish are dying and are very stressed. This has never happened before.

any ideas what’s causing them to die? The only thing that was changed was water and new heater. Nothing added to tank water. I checked ammonia and it’s normal. I don’t have any other test strips on hand. I did 20 gallon water change to see if that will help anything. 
 

thanks in advance! 

Edited January 2, 2022 by HollyJo
Autocorrected fish to gosh so I fixed it

[Levi_Aquatics]

I would check the temp to make sure the heater is actually working. I would also be concerned that there might have been a chemical in the heater that is poisonous to the fish. I have had a heater break before but that didn’t seem to negatively affect the fish. 

[lefty o]

if the temp is okay, it is almost certainly something in the water. did you use any kind of water treatment? for the future, i would only change 25-30% of the water at one time. if you feel the need to do more, do 25%, then a few days later do another water change of 25%. good things seldom come from large water changes.

[HollyJo]

I didn’t add any water treatment. The tank mates seem ok just the angels are stressing and so far one dead - 2 more not looking ver well. The temp on the side of my tank says 80 degrees so the heater is working. Is it possible that with the new heater shocked them by warming up too fast by going without a heater for a day?

[Kiefer]

Are you on municipal or well water? One thing to watch out for on municipal systems is superchlorination events. Many municipal utility systems will on occasion run a much higher than usual amount of chlorine through their systems in response to certain events, usually to nuke biofilms on system piping but sometimes when changing to a new source or after major rain events. So while you might normally be fine dechlorinating with the standard dose, if you get unlucky enough to do a big water change when this is going on your standard dose won't be enough to remove all chlorine, your normal dose will neutralize the same amount it always does leaving whatever else is left to cause major damage.

If it's killing this fast and everything else is normal excess chlorine would be my go-to guess. Most other contaminants aren't going to be taking your fish from perfectly fine to verge of death this quickly.

[GardenStateGoldfish]

If your on city water I would always add water conditioner, chloramine doesn’t break down so will kill all of your fish overtime. Chlorine will gas out eventually but will kill fish in the Process. 
 

if you think the new heater is faulty try removing it and observing if any more fish die, my angelfish tank is room temp and they do fine, I gave up on heaters when my last one failed and killed one of my three angelfish and also shocked me. I’ve had to many heaters fail I just will never use one again. 

[anewbie]

The heater might be leaching electricity into the tank or the old heater might have released something toxic into the water when it broke. Something is definitely wrong but hard to determine what.

[jhunholz]

Buy some test strips or an API test kit!  You should always have something on-hand to test the water parameters with.  Otherwise, we're just guessing blindly here.  Petsmart, Petco or your local pet store will have the tests you need.  Some fish stores even let you bring in a water sample and they will test it for free.

If the water parameters look fine after testing, I'm going to lean towards some chemical got into the tank from the old/cracked heater or as others have said maybe a problem with the new heater.

Do you have another tank? Even if its empty, I would move your fish over there with some fresh water.  Add some dechlorinator, wait 30 minutes and then add quick start or a different bacteria to start a quick cycle.  Another trick that can work for a quick cycle is to use Aqua-complete substrate (usually around $20/bag).  This comes with a lot of beneficial bacteria in it already.  My only caution is that this stuff tanks your PH, so you may need to buffer it up to where you need it!

[HollyJo]

I have 6 other tanks and did water changes on all Of them Thursday evening. The only tank showing any stress is the angels. The tetras, loch, pleco and female bettas seem fine in the angel Tank. It has to be something from that heater or the new heater. Ill Take the new one out and see how they do overnight. I’m on city water and have been for 16 years. Ive never had a problem with the water in all my tanks and I’ve never had to dad anything to the water. Im certain it’s something to do with the heater situation. Thanks for all the awesome advice!! 

 

[Flumpweesel]

You said you set the temp to 80 but have you checked that it is 80 (some heaters can be a little iffy on the dial) also what temp had the water dropped down to before you had chance to replace. Could the reheating have been a little fast and upset the more sensitive fish.

I believe you should step temp up and down quite slowly for some fish.