Help dying fish

[fishywishywowoo]

I have a 15g tank up and running since Jan. It was fully cycled stocking 7 wcmm and 4 hillstream loaches. They were all fine then bout a month ago I suctioned the gravel. Big mistake. A few days later I lost a wcmm. Then a week or so /later I couldn't find 1 of the loaches. Found like a small hard bit of skin looking thing that I'm assuming was the lost loach. Since then lost another wcmm and today noticed another 1 is being sort of pulled up by its tail as if being suctioned? The others all look healthy. They eat every other day. Water parameters ammonia 0.25 nitrite 0 nitrate 40ppm on api test kit. Can anyone shed any light? Have I caused a mini cycle by moving the. Gravel?

Sent from my Nexus 7 using Aquarium Advice mobile app

 

[gilpi]

I have a 15g tank up and running since Jan. It was fully cycled stocking 7 wcmm and 4 hillstream loaches. They were all fine then bout a month ago I suctioned the gravel. Big mistake. A few days later I lost a wcmm. Then a week or so /later I couldn't find 1 of the loaches. Found like a small hard bit of skin looking thing that I'm assuming was the lost loach. Since then lost another wcmm and today noticed another 1 is being sort of pulled up by its tail as if being suctioned? The others all look healthy. They eat every other day. Water parameters ammonia 0.25 nitrite 0 nitrate 40ppm on api test kit. Can anyone shed any light? Have I caused a mini cycle by moving the. Gravel?

Sent from my Nexus 7 using Aquarium Advice mobile app

I'm not sure why you feel it was a mistake to vacuum the gravel, you should vacuum it, lots of gunk like poop and uneaten food settles in it.
95% of your beneficial bacteria lives in the filter after it's gone through a cycle and that is what you should be careful cleaning. Never change the filter media, just rinse it and put it back in the filter.

 

[Sambo7475]

If it's the first time you've cleaned the gravel since setting up the tank, you could have released some mold or other fungal spores that could have irritated your fish. As counterintuitive as it sounds, I would do frequent small water changes for about a week. Thoroughly clean the gravel each time, and keep an eye one what comes out. If it's black moldy clumps, it may be junk that has been building up all this time, and needs to come out.
If you're still seeing nitrates, I think your beneficial bacteria are still doing their jobs (no mini cycle). What's your normal amm level?