Dead Fish, Dying Fish??

Hey guys,
Couple of questions for the experts here. You guys have seriously helped me out in the past.

So I moved house and moved tank and I thought it was successful however I've woken up this morning and I have a dead minnow. So sad. I'm going to test the water to see if I've somehow messed up my cycle. I'm hoping this is just a coincidence.

Before the move I noticed my paradise fish has become very slow. Usually he is darting all over the tank but for the last 2 weeks he seems to just be resting. He is eating and pooing, and he moves when prodded (I thought he was dead when I found him resting behind the filter hence the prodding). Now question, could it be illness i.n which case ill quarantine him, or is it normal fish behaviour for them to slow down? Do fish slow down before they naturally die??

Also I would love to get some more minnow. I have 7, a bn pleco and a paradise fish in a 29g. How many more minnow could I get? I don't want to over stock them but my tank looks empty of fish! Obviously I will not purchase any fish until I know what's going on with cycle/paradise fish.

Thanks for reading

Ok just gone to scoop the dead minnow out and he isn't dead. Also noticed another minnow on the gravel.
Why are some of my fish laying on the floor....?

Right I need to test the water and the tap water here...

Nope there is a dead one.

 

Ok just tested the water.
Ammonia 0
Nitrite 0
Nitrates 80

Tap water nitrates 40.

So I will do a water change (I usually do a water change every 2 weeks), it's been 10 days since the last one (was a 90% change as we had to move tank).

Is this the likely culprit? Nitrates. In my previous property the nitrate level in the tap water was similar and it never caused an issue.

Any other suggestions?

Current situation:
1 dead minnow.
1 minnow that is laying sideways on bottom but can swim to top for food.
1 paradise fish that is more sluggish than usual.

 

Paradise fish are as tough as nails. They don't sicken easily.
Circumstance says it was probably a result of the move. Could they have gotten quickly chilled? Did you remove chloramines in the first large water change.
Did you do regular, weekly water changes in the tank for weeks before the mega change with the move?
Still, a move 2 weeks ago - problems should have shown within days.
Is the new home cooler than the old one? What's the temperature like? Those are cool water fish, but gradual changes are what they like.

 

Paradise fish are as tough as nails. They don't sicken easily.
Circumstance says it was probably a result of the move. Could they have gotten quickly chilled? Did you remove chloramines in the first large water change.
Did you do regular, weekly water changes in the tank for weeks before the mega change with the move?
Still, a move 2 weeks ago - problems should have shown within days.
Is the new home cooler than the old one? What's the temperature like? Those are cool water fish, but gradual changes are what they like.

Navigatorblack, thank you for replying.
Yep I used water dechlorinator. I have always done 50% water change every 2 weeks.
My new home is warmer.

I've just checked the temp and it's at 19c. I think my heater has broken. It's set at 22c. Oh no. I can't believe I didn't check. Is this it?

I brought 2 paradise fish but 1 died. I was trying to get it better but its stomach ended up on the outside of it's body and I had to euthanise it. Throughly traumatic. This was months ago and everything has been fine with the other one until now....

Am I likely to have more deaths until I can get a heater?

 

If you're water temp has dropped from what they have gotten accustomed to it could be the cause also it could be that your tap water is different.

 

Tested pH? If it crashed it can kill fish.

 

I've not tested the ph no. Good shout.

When I moved the tank I bagged up the fish then done the whole slowly acclimatise to the tank thing. Would this not prevent shock?

Also, as navigatorblack said, would the issues not have arisen sooner?