I don't think I like my tinfoil barbs anymore.

[Dégatdeau]

I got 5 little altus tinfoils early December 2020. I grew them out in my 225 with bichirs. They got fairly big fairly quick. They were fine in there, no agression towards the bichirs, and none from the bichirs towards the barbs. I don't know what happened but they started killing themselves.

The first time it happened I was sitting in front of the tank. Not doing anything, just watching, as I often do in the evening. One of the biggest one threw a fit and started bashing it's head in the glass cover and the walls of the tank. I couldn't do anything, it was over in a second.

Couple weeks later, it happened again. The fish died in the same manner. I am down to three and they are jumpy af.

Has it ever

 

[Trouser Cough]

I'll take a stab at it at the risk of making an unpopular statement.

Tinfoils are peaceful fish. They don't bite, they aren't jerks, they are highly social and attempt to stay in a tight group when there's a predator nearby and quick to get away from trouble if they can. A quick escape is their only defense and you can see their grouping behavior in every shot you've provided. I can't imagine any situation where they might demonstrate aggressive behavior toward a bichir.

Many posters on this site seem to be quite taken with Bichirs; a carnivorous fish found in the fossil record that will happily consume just about any other fish up to about 2/3rds its own length.

You have combined the two in the same relatively small tank w/ absolutely no place for a peaceful fish to get away. Once you turned off the light over the last 100 nights the space became a 'stay awake or die' territory and that you're seeing odd behavior shouldn't seem a surprise. This is an issue that should have been prevented with a little independent research pre-purchase.

That they are "jumpy af" is to be expected given the conditions you've required them to live within.

My apologies if my response is not served gently enough. This is not a problem with tinfoil barbs.

 

[Dégatdeau]

I have a hard time imagining a 12" bichir taking a shot at a 10" tinfoil barb that's 4" high. But they do look stressed. I didn't meam it like I don't like tinfoils. I mean it like I don't like keeping them in that tank anymore

 

[Trouser Cough]

Bichirs are prehistoric predators with very bad geometry skills. They will take a serious crack at consuming other fish irrespective of reason and I suspect that the day will come when you flash the light on in the morning and notice one bichir hanging out of another's mouth with no way for the winner to swallow the loser.

I'd bet a nickel that if you take the barbs out of that tank and put them in another that doesn't have prehistoric predators in it you'll find that your tinfoil behavior will go back to normal. When the problem is anxiety in the tank look first to the type of fish you're attempting to combine. It is easy to make an error in that regard and it's easier yet when the crew at your LFS say "yeah... you've got a big tank, shouldn't be a problem".

When they were young it was a big tank. Not so much now that they're ten inchers.

 

[Trouser Cough]

You're absolutely correct about the 10" x 4" thing making it seem unlikely that the bichir would think that's ideal prey.

The anxiety doesn't necessarily come from the tinfoils having watched one of their number being eaten. The anxiety comes from the constant threat of being around something that is constantly sending the "I'm going to eat you" signal.

The second aspect is that when they're young the tinfoils could get from one end of the tank in 1 second and the bichirs could not. Now the tinfoils can get to the other end of the tank in far less than one second and the bichir would be right behind it.

 

[Ogertron3000]

The other answer is probably more accurate but i was thinking its a bright and open tank. Maybe reduced lighting and some floating plants and a bit more cover would chill them out a bit?

 

[Trouser Cough]

The other answer is probably more accurate but i was thinking its a bright and open tank. Maybe reduced lighting and some floating plants and a bit more cover would chill them out a bit?

Bichirs are nocturnal. Dimming the lighting enhances their instinct to hunt.

I don't have anymore constructive input here so this is my last post on the topic however, unfortunate as it may be there is no bandaid for the issue you're seeing. It is nature and the only correctible aspect is to remove the unfortunate pairing. Your tinfoils are a small group of Poindexter accountants that have been stuck in a prison's general population. For the tinfoils it will work out poorly.

 

[Joshuakahan]

You're absolutely correct about the 10" x 4" thing making it seem unlikely that the bichir would think that's ideal prey.

The anxiety doesn't necessarily come from the tinfoils having watched one of their number being eaten. The anxiety comes from the constant threat of being around something that is constantly sending the "I'm going to eat you" signal.

The second aspect is that when they're young the tinfoils could get from one end of the tank in 1 second and the bichirs could not. Now the tinfoils can get to the other end of the tank in far less than one second and the bichir would be right behind it.

That’s quite an answer, but I don’t know if it’s accurate. I had a 4x2x2 with a single 6” TFB and a few bichirs and few other predators and there was no issues. I did have dim lighting and floating plants. I imagine a single TFB would be more stressed in that situation and mine wasn’t, it would even steal food from the bichirs occasionally
My guess would be some kind of shadow is spooking them or water quality/parameters

 

[Dégatdeau]

That’s quite an answer, but I don’t know if it’s accurate. I had a 4x2x2 with a single 6” TFB and a few bichirs and few other predators and there was no issues. I did have dim lighting and floating plants. I imagine a single TFB would be more stressed in that situation and mine wasn’t, it would even steal food from the bichirs occasionally
My guess would be some kind of shadow is spooking them or water quality/parameters

The lightening is quite dim on that tank. It looks well lit in picture but in person it's only a 36" fluval aquasky that I run at about 30%.

I have tried plants with them when they were small and they ate everything. All of them.

And as for water parameters, I guess you could call them stable. The tank is on a filtered drip no ammonia, no nitrites and 5-10 ppm of nitrates.

 

[Dégatdeau]

You're absolutely correct about the 10" x 4" thing making it seem unlikely that the bichir would think that's ideal prey.

The anxiety doesn't necessarily come from the tinfoils having watched one of their number being eaten. The anxiety comes from the constant threat of being around something that is constantly sending the "I'm going to eat you" signal.

The second aspect is that when they're young the tinfoils could get from one end of the tank in 1 second and the bichirs could not. Now the tinfoils can get to the other end of the tank in far less than one second and the bichir would be right behind it.

I hear you. But I keep them in a 220, not a 55. They have ebough room to escape the bichirs that show 0 interest in them