Mystery of the Vanished Tetras

[crcurrie]

I'm helping my 9-year-old son establish and maintain a 28-gallon freshwater, planted tank. He had a year-old angel fish that he previously kept in a one-gallon tank, and along with him we introduced six neon tetras and four glass catfish. We also put in several ghost shrimp but they disappeared almost immediately (they tended to hide in the back around the tall plants and I suspect we vacuumed them out inadvertently with the siphon when doing the next water change).

When the tetras were first added, they stayed clear of my son's much larger angel fish, Stripey. However, Stripey is a timid, anxious soul, and never made the slightest aggressive move toward them, so that within a few weeks they paid him no heed. He, likewise, totally ignored them along with the glass catfish.

Unfortunately, we had a big algae bloom because we were using a powerful metal-halide bulb that was made for saltwater reef aquaculture. We ended up with a bad case of green water, which made it hard to see what was happening in the tank. We stopped using the light, and within a couple weeks the water cleared up. That's when my son noticed there were no longer six tetras, only two.

We looked carefully around the entire tank and found no carcasses. And the other two tetras, along with the other fish, all look and act healthy. It's possible, I suppose, that we vacuumed out the carcasses and due to the opacity of the algae-infested water, didn't notice them in the bucket. Or, even less likely, vacuumed out live fish -- but I doubt there is enough suction to take out a swimming fish.

The other possibility we could think of is that Stripey ate them. But since he still doesn't even seem to notice the remaining two, and they are still not afraid of him, and we haven't noticed him looking fat, or less hungry than usual (he's well-fed, probably over-fed, but always up for more), and it's been a couple of weeks now and neither of the remaining two tetras have disappeared, it seems unlikely to me that Stripey is the culprit.

Does anyone have any theories about what could have happened to our tetras? If they died, could it have been due to the algae bloom? My son and I are not only curious, but also concerned about whether we should try to replace the fish. We know tetras are normally not happy unless in a school of at least several of their own kind.

Chris

 

[tomtom14]

All the theory's you have had for the missing tetras are good. Green water does not affect the fish only the appeal of the water. I wouldn't try to replace the tetras as you will have a shoal of 4 and a shoal of 2 that won't won't look good. Hope this helps.

 

[absolutangel04]

Honestly, any of the things you suggested are possible. the angel might have eaten them. I personally had an adult angel take out a few neons I added to the tank. you won't see aggression when that happens, because predatory behavior is different. They tend to just grab a neon every once in awhile IME until there are no more neons. Also, small fish like tetras often decompose very quickly in a tank. If they had died while the water was green, it is quite likely that they would have decomposed before the water cleared. It is not too likely that you siphoned them out. Sometimes you might get a stray fish that gets sucked in, but not all of them.
Also, neons are known for dying off, especially when they are switching tanks. they are not generally considered the hardiest fish. So, it is quite possible that you got some weak stock that just didn't make it and then decomposed.
If you want another school of fish, I would suggest a different tetra that is too big to be angel food, like the pristella, diamond, rummy nose, black neon or lemon tetra. If you want the same look, you could try cardinal tetras. They get larger than neons, but sometimes finding ones large enough to avoid being eaten in the first place is sketchy. Another cool fish is the cherry barb or the gold barb. They don't school the same way that most tetras do, but are very fun to watch. My neon eating angel has never touched a cherry barb before.

 

[crcurrie]

Thanks for those insights. Regarding the die-off theory, we had the tetras for about six weeks and they all seemed healthy, then in the space of less than two weeks four disappear, then in the last two weeks, no more are gone.

I decided to observe Stripey by looking through a cracked-open door, so he wasn't aware of my presence. (Whenever a human is in the room, he focuses on him or her -- either begging for food or darting for cover, depending on who it is -- so it's not possible normally to witness his behavior when only with his fishy fellows.) I was surprised to find that he was quite active, swimming and darting about the length and breadth of the tank, poking around the plants and gravel, and even shooting up against the glass occasionally, as if practicing ambush behavior. This made me think that maybe I'd taken him for being more passive than he really is.

I guess I'll just keep an eye on the remaining two tetras, and for replacements of the missing ones, we'll not get more neons but try larger schooling fish. It's too bad, because I've always loved the look and behavior of neon tetras since I was my son's age.

Thanks again for the replies!

 

[corylover]

the only way to keep neons is in a school with same tempered fish that are of the same size. like fancy guppies I have now 4 neons and 4 fancy guppies 1 male guppy and 3 females. they are to preoccupied with breeding then messing with the neons and I had 6 neons but 2 passed due to a freak accident that got them injured (one having a bent back)and they lived only 2 months later. I have them in a planted 10g.i have no clue what happened I had all normal fish then woke to 2 injured.fish act completely different when they aren't in the presence of another being weather its human or animal like a cat or dog. because when I started out I had tiger barbs(don't recommend them unless you just want a tank of just them) and neons mixed in a 40g and they ignored them when I was there but then in one night the neons went bye bye not even all the bodies were found. and even if you had a tank of just the tiger barbs they still will fight to the death over who's boss. everyday too its just constant so I have 1 in the 30g and the other in the 40g waiting for them to grow old.