Been A While But Back Now With Fish Dying

Hi all,

Been a while since I last posted, things have been going fine even managed to get some decent plant growth.  Will add some pics shortly however... the reason I'm here is I'm losing fish. 

Originally I wasn't even seeing the fish going missing, I've read up that the shrimp more than likely had a feast.  I'm usually good at spotting deaths but with more and more plants it's getting difficult.  I honestly don't think the fish deaths are causing the rest i.e. I'm not seeing any ammonia spikes.

I noticed three weeks ago my Nitrate was at a level I couldn't read on testing (too red to really work out the level).  Bit of quick research and realised the plant fertislier I was using contained Nitrate and my tap water is already fairly high so I've switched to a fertiliser with no nitrate added and this switch happened about 3 weeks ago.

I use 50% water from spotless water solutions so 0% chemicals and then 50% tap water.  This is also to combat the very very hard water in my area.

Now my memory isn't the best but I reckon three weeks ago I lost a Harlequin Rasbora and Neon Tetra within 12hrs.  I've since lost another Harlequin Rasbora  and now one is sat on it's side on the bottom and if swims is summersaulting.  Other fish are doing well Cherry Barbs, white cloud minnows, black widow tetras, danios and honey gourami although I have noticed one of these is a pale yellow whilst the other 4 are a lovely bright deep yellow.  Actually not sure if they are honey gourami, they are bright yellow but they are not fall size gourami and maidenhead aquatics did have them listed and sold separate to dwarf gourami's.

I'll also add, I've gone from 11 neon tetras to 3 now over 9months and can't say I've spotted and got them all out the tank.

Anyway I know the score... water readings 

They are on route with the photos.....

Sorry to hear that you've lost several fish @Marcus_F
If you can get some pics of the fish & post along with your water parameters that would be really useful.
Have you added any new plants in the past 2-3 months? Have you added any decor? Has anything else changed? Have you changed/replaced filter media? Have you used any aerosols, scented candles or similar in the past few months?
Sorry if I'm going over things you've already considered, but any/all information may be useful for us.

Two pics, you can see how one is whiter.  Can’t say I’ve noticed it before but notice a fish loses colour when ill.

Generally we'd suggest just rinsing filter media in old tank water, rather than replacing media. I know most manufacturers suggest replacing, but it's not necessary, and you lose the good bacteria. I tend to syphon substrate into a bucket, then use the bucket to gently squeeze the filter media. With sponge or foam it's easy to tell when it needs replacing as it doesn't spring back in to shape.

Even with replacing filter media it's unlikely that it would have caused an ammonia spike that would have such a negative impact on the fish, but if it happened at a similar time to the introduction of new plants (if there was anything on the plants) and/or if there was a build up of gas from anaerobic bacteria in the substrate was disturbed while planting, it may have had an impact.

I've used the Tetra crisps with my fish and haven't had any problems. Have you noticed any behavioural changes in your fish?

I can see one of the fish is pale. I don't have any experience with gourami, but some of the others are very experienced and should be able to give some advice on this situation. Pale coloring is a symptom of dwarf gourami iridovirus, but I didn't think that would impact your other fish.

The harlequin rasbora at the bottom of the tank & spiraling while swimming may have a swim bladder issue.

Hopefully the others with specific experience will be along soon with some more advice.

Sorry for the misunderstanding. I read your previous message as you were replacing your filter media rather than cleaning it.
I agree that fish often seem to show the symptoms of laying at the bottom of the tank and/or swim in a spiral for a while before passing. I find fish disease diagnosis quite tricky. I don't feel as if I ever know enough about various diseases, and so many seem to have similar symptoms. 

Thank you, I'm thinking it could be a resulting factory of the high nitrates because as you say, I'm not sure for how long that was an issue.  Could take a month or two for any other fish suffering from it to a) recover or b) succumb.

The food crisps/flakes I didn't think would be an issue but the way the smaller fish can't seem to grab any food is worrying me so I've just ordered some original flakes, more for my piece of mind.  I tend to see fish swimming about with them in their mouths and then let go after 10 seconds in what seems to be a still 100% perfect disc with no bites.

As for the Hard water and soft fish, I was thinking the mix of RO water 50/50 mix would reduce this somewhat.  I must admit the tank has been running smooth for a year so I've not been testing but I don't remember GH being so high, I know KH was and the RO mix has dropped this from around 20 drops originally.  I shall have to go away and read up again on water hardness and the KH/GH readings.

I've not seen any bullying on the gourami, they often seem very peaceful and if anything despite more suitable for softer water and their known issues they are actually my most successful fish.

So i'm totally confused now.  The tank reads 21 drops for GH, I just completed a water change 25% and the water going in read 11 drops for GH.  Having added the new water the tank then read 18 drops for GH. 

My tap water reads 21 drops for GH as did my tank before the water change.

So what this tells me is I'm adding 11GH water but whilst in the tank it's increasing to 21GH.  Could I be adding something inadvertently that increases the GH?

I have live plants to dose fertilsers and liquid CO2 along with MgSO4 and phosphate.

I'm guessing one of the above is increasing the GH and it just so happens to mirror my tap water reading as a coincidence.