Not Again! What Am I Doing Wrong?

I set up a 55 gallon in December and so far I've had 26 fish in there, and 12 have died. I didn't really achieve cycling until April, and after that things were looking great. But then in late May, 2 cories expired, and in June a platy and a paradise fish have kicked the bucket. None had any visible signs of disease, and only one showed suspicious behavior (hiding out in an ornament while it's brother was very present).

I hate to acknowledge this, but I got a little lax on the water changes. I had been changing roughly every 2 weeks, and was adding fish steadily (2-4 fish every 2-3 weeks). That may have something to do with it, I realize. The last 2 deaths occurred within days after a water change.

Since mid-April, pH has been steady at 7.6, ammonia has been usually 0 (twice it was maybe as high as 0.25), nitrite 0. The nitrate had been 0 from day one up until mid-May, and it is now at 5.0.

In the original setup I used shower water but within a couple months started using R/O from a LFS, then transitioned to Glacier (which I've been using exclusively since early April).

Stock is now:
5 Buenos Aires tetras
4 platies
3 cories (2 emerald, 1 Schwartz)
1 paradise fish
1 zebra danio

Filters: Cascade 1000 canister filter, Slipstream 75 (HOB), Marina 20 (HOB).
Temp: 75-76 degrees (has been steady for months)
Food: Flakes and sinking pellets. I have also used frozen food but I noticed that I always seem to have a fish death after using it, so stopped using it after the May deaths

Picture is from 5/20. Nothing changed aesthetically since.

If I had to guess, I'd think it's the nitrates, but I haven't read anything to indicate that 5.0 or less should be lethal (I realize ideal is 0).

This venture has been soul-crushing. I feel terrible b/c I'm sure I'm doing something to kill them off, but I just don't know what it is. The fish are from various stores. In the beginning I went to the chain stores, when those fish didn't do well I switched to specialty stores and the fish were much better, but now those fish are dying, too.

 

I’m no where near an expert but from what I’ve learned here one thing that stood out to me is your lack of water changes. Once a week is the minimum on most tanks from the research I’ve gathered, unless you’re incredibly under stocked in a large tank that has live plants and is very well established.

I also don’t know if 26 fish is a bit overstocked in a 55 so I’ll let some other member comment on that.

Can you explain what “shower water” is? Is that rain water or..? Are you using water conditioner? I know a lot of people who use things other than tap water don’t but I think it’s risky not to use water conditioner considering it’s not even expensive and it can (and does) save your fish.

As far as I know, cories need clean water that is high in oxygen and a good supply of food, people often mistake them as the “clean up crew” but they’re actually primary carnivores from the knowledge I’ve gathered (someone correct me in I’m wrong).

 

Your Nitrates are perfect so it's not that. Don't know what it could be. I know I had a Cherry Barb die the other day, no signs of sickness, just died. But for you to have so many, it sounds like something isn't quite right. I don't know much about Paradise Fish, can they be aggressive? Do your fish seem to get along? Are they picking on each other? I think my Betta may have stressed my Cherry Barb by chasing him, just a theory.

EDIT: Just did some quick research, and it seems the Paradise Fish are quite aggressive. So you may want to watch for that.

 

Your Nitrates are perfect so it's not that. Don't know what it could be. I know I had a Cherry Barb die the other day, no signs of sickness, just died. But for you to have so many, it sounds like something isn't quite right. I don't know much about Paradise Fish, can they be aggressive? Do your fish seem to get along? Are they picking on each other? I think my Betta may have stressed my Cherry Barb by chasing him, just a theory.

EDIT: Just did some quick research, and it seems the Paradise Fish are quite aggressive. So you may want to watch for that.

OP stated that one of the two paradise fish died.

Doesn’t sound like a bullying issue to me honestly.

 

OP stated that one of the two paradise fish died.

Doesn’t sound like a bullying issue to me honestly.

Was the other Paradise Fish male or female? Profile says they WILL fight with other male Paradise Fish.

 

Welcome to FishLore!

Two things strike me as a little unusual right off the bat. The first is that if you are using shower water (which I'm assuming means rain water) or RO water, what are you doing to get your pH up to 7.6 and holding steady. Usually without additives both rain water and RO water are pretty soft, and therefore have a low pH, GH and KH.

The second thing is that even though you seem to have a pretty heavy stocking, your not getting very much in the way of nitrates. And that is especially surprising considering that you were lax with your water changes. In a cycled tank, fish constantly produce ammonia. That ammonia then gets converted into nitrites. then those nitrites get converted into nitrates. But since there is nothing to convert nitrates, they just build up in the water until a water change is performed to lower them (that is one of the main reason for doing water changes).

 

I had the same problem when I first got into fish tanks about 3 months ago, I kept losing more and more fish and I couldn't figure it out. Are you vacuuming the substrate? What type of substrate are you using? Do you have live plants? Are you using a water conditioner? These are all things that can effect the fish easily. Also is you water paremeters matching what fish you have? I found out too late that my ph was high for some of the fish I had and low for others and I have a feeling that contributed in their deaths so now I'm more careful. Also you need at least 6 danios. They are a schooling fish.

 

Welcome to FishLore!

Two things strike me as a little unusual right off the bat. The first is that if you are using shower water (which I'm assuming means rain water) or RO water, what are you doing to get your pH up to 7.6 and holding steady. Usually without additives both rain water and RO water are pretty soft, and therefore have a low pH, GH and KH.

The second thing is that even though you seem to have a pretty heavy stocking, your not getting very much in the way of nitrates. And that is especially surprising considering that you were lax with your water changes. In a cycled tank, fish constantly produce ammonia. That ammonia then gets converted into nitrites. then those nitrites get converted into nitrates. But since there is nothing to convert nitrates, they just build up in the water until a water change is performed to lower them (that is one of the main reason for doing water changes).

These days RO units can buffer the pH up or down, depending on what you want.

 

Clarification: I don't have 26 fish...I have 14 but a total of 26 have lived in it at one time (high was 18).

By shower water I mean water from my shower which I know has a very high pH...but did water changes with RO and then Glacier from March to present.

Gravel substrate, which I do vacuum, no live plants, do use conditioner.

The paradise fish have shown no aggression to each other or to any other inhabitants. The Buenos Aires tetras, one or two in particular, have chased each other and sometimes the platies or the danio.

I do intend to give the danio friends; it was going to be the next one increased but with the recent deaths I don't know what to do.

P.S. I have no idea why my pH is still so high, given that since March I have only put in water with neutral pH. I looked into driftwood but LFS said I would need a lot for a 55 gallon and so cost and tank real estate was an issue there...they convinced me to buy Seachem pH regulator...tried it a couple days and no change, and further research (inc. this site) kind of scared me off it.

 

I would not be concerned with your pH. A steady 7.6 should be fine.

 

So your PH is still 7.6? Why are you worrying over that, it’s actually ok.

Try doing weekly water changes for a few weeks see if things improve.

 

It could be a disease that can’t be easily detected. A few months ago I lost 8 fish over the course of three weeks with no explanation.

Are you sure there were no other symptoms? Raised scales? Faded color? Shrunken belly?

 

Ph isn't really an issue unless you get drastic fluctuations or you get fish that need a much higher or lower ph. Best bet is to wait it out, do frequent water changes for awhile, don't by new fish, let things settle. Could be a minor problem that just needs the beneficial bacteria in your filter to just work it's magic. Remember with any water changes do conditioner, no matter the type as even store bought water can have chlorine and other problems with it. Took about 3 weeks after I stopped buying fish for my tank to finally settle and my fish to stop mysteriously dying with no issue seeming to be the problem. If you wash decos remember to used conditioned water, when you clean the filter use conditioned water. How long have you had the tank? It might just need to settle for a bit.