Trouble with Lemon Tetra

[DJNut]

Hi, the tank's had fish in for 6weeks, it was fishes cycled. I put the lemons in at the beginning, but I'm struggling to get the lemons to eat, and they don't come to the top for food I feed a mixture of flake, sinking pellets, dried daphnia but if I don't feed the fish for a day(been away a few times recently for a day or two) , I find dead tetra. In the tank are, and four angelfish, 4 Bolivian rams, 4 mollies(from previous tank) , now 8 lemon Tetra, there were 12.
It's AquaOne 400l tank,
ammonia 0, nitrite 0, nitrate 10, 6kH,
I change 100l of water a week, though in the last week I've done 200 in total, and will be doing another 100 later.

Do other people's tetra come to the surface? Mine always stay mid to bottom

I'm wondering if an even bigger school would help them.

The mollies are aggressive feeders, I'm tempted to re-home these, I've had them over 9months, they were the Mrs' choice, do fish stores take fish off your hands?

Many thanks for your time, sorry if I've missed any useful info off.

 

[Samzter]

What size tank is it?

 

[DJNut]

AquaOne 400 litre

 

[Samzter]

Don't worry i know its a 400 l . Is there any aggression in the tank? That could be a problem since there is a few angels. I take it you cycled your tank using fish , A that's not always a great idea, especially if you cycled it with lemon tetra. They are sensitive to water parameters so I think that might have something to do with it.

 

[Samzter]

Yes personally I would boost the school up add another 8

 

[DJNut]

Sorry my phone auto corrected that, it was a fishless cycle, the angelfish are still young and peaceful and there so much room they can stay far apart.. The only one that gets a bit bullyish is one of the mollies. Thanks for your reply.

 

[Samzter]

I'm not sure then, I would probably boost up the school to make them feel more secure

 

[DJNut]

Thanks I think I will, I got a bit worried about about adding fish whilst fish were dying