Bad choice of names if that's how they treat customers.

I don't know what to recommend other than getting the african cichids out of there.

What size / model sponge filter is it?

It looks like you threw off the balance and started a mini-cycle.

Those kitumba are Lake Tanganyikan, as I'm sure you know. They aren't the most aggressive of african cichlids but it isn't a good mix for either especially given your water parameters.

I would get them out of there asap. There ...

What about nitrates? And have you tested all your water parameters since you put them in?

Also, what size tank is it? Are there any other fish in there or was it a fishless cycle?

I simply asked Jeff Rapps about it and I'm satisfied they were sold to him wild caught.

I don't know him personally but I know he has a solid reputation in the hobby.

Decent guy too from my brief conversation via email.

The worms are probably in your filter media since you have no substrate. Clean that out too.

When and how much was the last water change before the 80%?

No need to take a pic other than me being happy to see the tank....

OK, zero nitrates in a bare bottom non-planted tank is not possible.

Population explosions of worms occur when there's excess feeding or nutrients in the water.

You probably have a bad test kit if it showed zero, unless it was higher than 0 before you did an 80% water change.

Why did you do the ...

Is this a heavily planted tank.

There's a reason for the questions.

And your nitrate?

How long are these things. Looks like a real close up pic.

I would still cut back on the feeding and check the nitrates.

I waited for 2.5-3 years. One breeder in my area seem to get fry from August to december for the past few years. I got my first batch at the end of November and I'm on my 4th batch as of last week.

The fall was milder and this winter has been a bit harsher than the past few years. Maybe that has ...

It could be planaria. How much are you feeding? Cutting back will probably clear it up. Also gravel vac the substrate when you do your weekly water change. Last, bettas and gourami's will eat them.

I assume you aren't putting the zebras in with the ABN though correct?

I have never heard of the deformity but 10-20% daily water changes to keep the nitrates at 10 raised a flag along with the low KH / GH if those readings are degrees.

low KH can cause ph swings and if you were doing weekly water changes your nitrates could reach toxic levels. More frequent water ...

Can you get a picture of one? When mine eat a bit too much, their bellies are the only thing to touch.

But as for the overall health, 20 nitrate is about as high as you want it. When was the test performed in relation to your last water change?

High nitrates become toxic and fish get sick as a ...