Ammonia spike

[dmaccy]

Hi all - I have recently noticed an ammonia spike in what is an established tank. Noticed immediately after testing after a fish death. Only change to the tank was the addition of three new fish, 2 flame tetras and 1 julii cory. Cory was dead within 48 hours of arrival. Is it possible such a small addition could cause a spike?

Usual maintenance routine of weekly water change and gravel vac

For info all other parameters, including NO2 testingg ok. I.e as usual.

 

[mcordelia]

first order of business would be to do daily 50% or more water changes until the ammonia gets under control. How big is the tank? what other fish do you have in there? how old is it? Do you have plants? What do you have for filtration?

 

[dmaccy]

60 litre tank

Fish stock now 3 juli cory, 7 flame tetra and 6 black emperor tetra

Been running for approx 9 months

Plants = pink Reinickii, twisted vallis and a couple of cryptocoryne

Filter is the tetra filter which came with the tank.

 

[Colin_T]

yes, one dead fish can cause ammonia levels to skyrocket very quickly.

 

[dmaccy]

Ammonia is still high now, sat about 0.5.
How long should I expect before it reduces naturally?
NO2 still reading zero

 

[Colin_T]

If the filter is established and nothing else is rotting in the tank, the ammonia level should come down within 12-24 hours.

The safest thing to do if you have an ammonia or nitrite level above 0ppm, or a nitrate level above 20ppm, is a 75% water change and gravel clean the substrate every day until the levels are 0ppm.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.