Fish deaths and stress, can't determine cause (a bit long)
Hi all, I'm having some issues with my 29 gallon tank. It's been fully cycled for two months now and I regularly check levels with my master kit. The tank is the planted tank in my profile. Everything was going well, I had stocked two schools, 8 Bloodfin Tetra, and 8 Zebra Danios. They were so active I was calling it my "fish in a blender" tank and everyone seemed pretty happy. The Danios were spawning quite a bit. Over the past week I've lost all but 2 Danios (2 at a time, overnight) and the Bloodfins spend a lot of their time huddled together behind a piece of driftwood planted with Java Fern. They are all eating well.
My normal routine was a 50 % water change every 6 days with gravel vacuuming of the areas that wouldn't disturb the plant roots. I use Prime for my conditioner. My ammonia and nitrite were consistently 0 but my nitrates were inching up towards 40-ish (seems like there are always bits of plants decaying no matter how I try to "garden"). pH is 7.4, no change, and temp is 77.5. I decided to get a water changer to make the changes easier last week and I did two 50% changes 3 days apart to get the nitrates down to a more manageable level. That's when the deaths and stress behavior started. I was very careful to add enough Prime before I refilled the tank with the changer, the water temp was within 2 degrees of the original water. I added enough Prime for a 50 gallon to be safe because it says you can safely double dose and I was a bit paranoid about adding tap water straight to the tank. I would have thought the water changer would be less stressful because I'm not having to pour water back into the tank and disturb anything.
The only thing I can think of that may have made a difference is that I lifted the two pieces of driftwood and vacuumed under them on the last change. Is it possible that I disturbed an anaerobic pocket? From my reading I thought it would take much longer for those to occur, and I do have snails in the tank (hitchhikers and 4 assassins to deal with them, although I'm not sure if all the assassins are still alive, they hide so much) so they should be helping with the aeration, right?
I'm a bit frustrated at the moment because everything SHOULD be fine but something obviously isn't. Any suggestions would be helpful.
Your nitrate levels are pretty high. Are you over feeding? What kind of food do you use?
I know that snail deaths result in a explosion of ammonia. Is it possible that you could have missed that?
Have you added any salts or products besides Prime?
What kind of filter are you using? Did you ever wash the filter? Was the filter ever left off for significant amount of time?
What kind of substrate are you using? How deep is it?
Have you recently added any fish? Do the fish look bloated, swim strangely, or have any unusual marking or spots on their bodies? Does anything hang out of their butt? (Weird question I know)
The filter is a Marineland 150 Biowheel, I rinse the media about every 2 weeks in tank water and make sure the biowheel is still turning. I was a bit concerned about the nitrates too, that's why I did the two water changes (I know that if I only do 50% I'm not removing them all and eventually they will keep adding up so I wanted to lower them more significantly). I thought I might be over-feeding so I have reduced my feeding (Tetra flakes) but that was all BEFORE last week when the issues started. After the second water change the nitrates were at 10, which is pretty good for me because the tap water comes out at 5 and that's when the problems started, when the nitrates were actually lower.
My substrate is gravel, about 2 inches, regularly vacuumed where I can. No medications or salt added and no ammonia spikes so even if there were snail deaths the BB seems to be taking care of that. Honestly though, I have no idea how many of the four snails are still alive because I see them once in a while but they tend to hide.
The fish looked fine the day before and I'd get up to 2 dead fish. The Danios seem to be really big with eggs a lot of the time though, so I have no idea if I'm having egg bound issues or if there is something else going on. I know they are spawning though because I moved a Water Sprite from that tank over to my Betta tank and 2 little fry hitchhiked along with it.
I hate to get more fish until I have a better idea of what might be going on but I'm somewhat at a loss.
I don't think I see anything here that might explain this, so we need to examine a bit closer.
The rise in nitrates is interesting, they should remain stable if the tank is now looking much as it does in the photo with those plants. [Nice aquascape, by the way.:-)]
If using the API liquid nitrate test, are you shaking Regent #2 for a good 2 minutes before adding the drops? If not, do this and see what reading you get. And nitrates in the tap water with this kit are 5ppm, just to confirm?
Adding Prime when you begin to fill with tap water is fine; it is instantaneous. There is no chance of chlorine poisoning with this.
Are the fish showing anything odd, in colour, appearance--spots, blotches, patches, frayed fins, closed fins... anything? Are the bloodfins harassing the danio at all? And these fish have been in the tank how long?
Hi Byron, the fish have been in there for 6-8 weeks (I added them about 4 at a time over a couple of weeks) and were very active and eating like little piranhas. Both schools chased each other around within their own schools but not really Danio to Bloodfin or vice versa. No real aggression or nipping, just really active. I seemed to have 5 or 6 female Danios and they constantly appear heavy with eggs, at least to my inexperienced eye. There didn't appear to be anything wrong with them and I usually sit and watch them eat to see how everyone is doing.
I'm very careful to shake and tap and do the Cha Cha with the Nitrate bottle each time and they've never gone over 40-ish but with the two water changes last week I was trying to bring that down further. I've tested the tap water a couple of times and it's always 5 ppm and the water utility report also verifies this. My plant growth seemed to have stalled a bit so I pruned back the Water Sprite during the water changes to add a little more light, so the tank was brighter than it had been. I can see that possibly contributing to the stress but not the deaths. I use Seachem Flourish and root tabs for the plants. I did add more of the tabs with the last water change but they were overdue (the ones I had were API and say they last a month).
The Tetras did come out and get more active tonight but are staying near the bottom of the tank. The two remaining Danios are behaving normally and are active and near the top of the tank as usual. I'd like to replace their school but it's a little scary at the moment!
I failed to mention that I'm having a bit of the new tank brown algae but after reading up on it I'm not too worried about it just yet. I noticed tonight that there's a light sheen of green algae on the tank walls (you can see it if you look at the tank from the end) but I'm assuming that's because I added more light and had the higher nitrates and slower plant growth for a while. I'll scrape that off with the next water change.
have found two useful websites the url’s
Aquarium Nitrates; Lowering Nitrate Levels, How to Control
Aquarium Nitrogen Cycle and cycling. Methods for ammonia, nitrite removal.
interesting point about canister filters being nitrate factory
Thanks Byron and Pops,
I did another water change today and they are starting to act normal again. I know my nitrates were a little higher than they should be but I can't think why after a water change that brought them down to 10 that the deaths should start. I'm beginning to think I must have disturbed a pocket of something when I did a more thorough cleaning.
Moving ahead, I'm not going to add any new fish for a while and quarantine the new ones if I do. I will lower my feeding amounts and see if if this will help the nitrate situation. I believe I had a pretty large snail population hiding in my gravel because today I figured out that all the little white things whirling in the siphon were empty snail shells (small, about 3mm) so the Assassins must be having a good time in there, but that population must have contributed to a higher bio load than I thought I had.
Thank you for trying to figure this situation out, hopefully things will settle back down and MY stress level will decrease :)
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