SFDS - Spontaneous Fish Disappearing Syndrome

I may have just made that up, but I've lost a few fish over the course of the last few weeks. In my 55 that has been fully cycled and operating like clockwork for probably 7 or 8 months now, I have had 3 fish disappear over the last couple of weeks: 1 male Fancy Guppy, 1 Black Molly, 1 Black Neon Tetra. In the tank, I have a few Angelfish, a Pleco, a few Albino Corys, 4 other Black Neons, a Dwarf Gourami and some Zebra Danios. Other than an occasional territorial, yet mild skirmish between the Angels, it's a very peaceful, though energetic tank.

I thought that perhaps the Black Neon maybe got eaten by a hungry Angel, but they've been together in that tank for probably 4 months and I've never seen them show any interest in them. The Black Neons are also not tiny. There's nothing big enough in the tank to go after the Molly. Again with the Tetra and maybe even the Guppy, I wondered if I had maybe accidentally scooped them up with my siphon during a WC, but I really think that I would have noticed that, plus the fish all typically steer very clear of the syphon.

There is no trace of any of the three. No fish currently appears ill in the tank, and none of those three appeared ill either. Parameters are great: 0 Am, 0 Nitrite, 10-20 ppm Nitrate, PH 7.6, Temp aroune 77 degrees F. I've had these fish for months and haven't added any since probably the Black Neon Tetras in October.

I'm stumped! Any ideas on what happened?

 

Either a death by natural causes or murder. The bottom feeders as well as the other tank mates can make short work of a small corpse.

 

Yikes!

 

Yeah fish do sometimes just die. Than they become a meal for the rest. Life spans on fish are pretty much guess work. What you read is how long some survive. As long as the rest look good your ok . How often do you change the water?

 

I typically change the water every week.

 

Ok so your water is good so it’s just natural causes. Again fish do die. A few months back I had my favorite discus only about 6 month old just up and die. Nothing else in the tank just that one. As long as the waters clean there’s nothing we can do.

 

Yeah, I figured it was along those lines. Never fun. I was hoping that I messed up something and I could learn from it.

 

If it helps... I don't know what's in my tank anymore..
I don't know if somethings are just hiding or passed on !

 

Lol! Yeah, I think that's coming now. I just added four KuhlI Loaches yesterday and after the initial release, I've only seen a couple of them. I'm not worried as I know they are nocturnal and it will take a little time for them to get comfortable in the tank.

 

We have experienced something of a related phenomenon at our home, Spontaneous Reappearing Fish Syndrome. For example, a couple of months ago, we seemingly lost a young swordtail kaiku that we really liked, even though we didn't find a body, and so we bought another one about a week later. A couple more days later, we did a partial water change, cleaned gravel, etc., and woa - two young swordtail kaikus swimming around. We had something similar happen, where a school of six neons, which had dropped to five, became six again after another tank cleaning four days later!

The only possible answer that we could come up with, is that the fish were somehow getting trapped inside a large aquarium decoration that we have, like this one:




We have been more careful to ensure that the decoration was firmly planted into the gravel, with no space underneath, and we have not experienced SRFS since.

 

That's a good point. I have a couple of large decorations and that thought has crossed my mind, though I feel like I have moved them for cleaning since...but it's a possibility. The two main decorations that I have will be leaving the tank at some point over the next couple of months as I successfully transition to more of a planted tank. For now, they are there and at least offer nice hiding places for my pleco and my new KuhlI Loaches.