Axolotls With Bkfs?

[JoshuaC]

Will an Axolotl make good tank mate for a Black Knife Fish? They grow to about the same size in when they're in tanks so it doesn't seem like a problem to me but I want to get other people's opinions.

 

[ZoddyZod]

Axolotls should really be kept on their own. They are very predatroy and may take a chunk out of the BGK - depending on the size.

They really should not be mixed with fish.

 

[nmonks]

Agreed; this is an incredibly bad combination.

Apart from the predation aspect, which is 100% correct, Axolotls also need fundamentally different water conditions -- cool, hard, alkaline water. They are also extremely messy (can you say "high nitrate levels"?) and are significantly less sensitive to ammonia and nitrite than almost any fish (your fish will be dead long before your Axolotls seem unhappy, which is a problem with nocturnal fish that hide a lot).

Black Ghost Knifefish are extremely difficult to maintain. I'm not saying they're impossible to keep, but ask yourself how many ADULT specimens have you ever seen in home aquaria? I've seen lots of big fish returned to pet shops because their owners couldn't keep them -- Clown Loaches, Plecs, Oscars -- but I have NEVER seen an adult Black Ghost. My guess is fewer than 1 in a 100 is kept alive for more than a couple of years. In other words, you absolutely must focus on providing the optimal conditions for your BGK, and if you want to keep tankmates, choose some small (not bite size!) schooling dither fish species that won't affect water quality much.

Cheers, Neale

They really should not be mixed with fish.

 

[ZoddyZod]

Neale - I think it was possibly one of your PFK Q&A responses where I got the predatory nature of Axolotls from. Hadn't know that side of them until then.

 

[nmonks]

Ah, yes, sounds familiar. These animals are pretty cannibalistic, let alone being safe with fish! It's quite common for them to bite one another's toes off.

Cheers, Neale

Neale - I think it was possibly one of your PFK Q&A responses where I got the predatory nature of Axolotls from. Hadn't know that side of them until then.

 

[Squidward]

Neale,

I have had my BGK for obout 3 1/2 years.
No special conditions, just "standard" tropical fish treatment.

It got to about 25cm and has seemed to stop growing.
One never seems to see fish of 45+ cm that one sees quoted.
Is that just something due to captivity?
Or are these figures unreliable?

Thanks
Squidward

 

[nmonks]

Three and a half years is VERY impressive; for what it's worth, you definitely get a "well done" from me! I do suspect what you call ordinary fishkeeping is actually very good fishkeeping in terms of water quality, water changes, diet, etc.

Baensch reports that a specimen got to 45 cm in 16 years; whether it grew continually at the same rate over those 16 years to reach its final size I cannot say. But I think there's an indication these fish are long-lived. At the Bolton Museum aquarium they had a related species that was huge. Admittedly, it's a species that gets twice the size of Apteronotus albifrons, but it does suggest that South American knifefish can get quite big under aquarium conditions.

Cheers, Neale

One never seems to see fish of 45+ cm that one sees quoted.
Is that just something due to captivity?
Or are these figures unreliable?

 

[Squidward]

Three and a half years is VERY impressive; for what it's worth, you definitely get a "well done" from me! I do suspect what you call ordinary fishkeeping is actually very good fishkeeping in terms of water quality, water changes, diet, etc.

Baensch reports that a specimen got to 45 cm in 16 years; whether it grew continually at the same rate over those 16 years to reach its final size I cannot say. But I think there's an indication these fish are long-lived. At the Bolton Museum aquarium they had a related species that was huge. Admittedly, it's a species that gets twice the size of Apteronotus albifrons, but it does suggest that South American knifefish can get quite big under aquarium conditions.

Cheers, Neale

Neale,

Thanks!

It is in a 250L tank with plenty of wood hiding places.
I do a 25% water change once a week.

Diet: Tetra Prima, minced fish, minced prawns, freeze dried river shrimp, frozen blood worms, forzen brine shrimp
I have also noticed that it picks on the fresh greens I put in for the Plecs.

This one is relatively placid, hiding most of the day, and coming out to eat at night.
It leaves the other fish in the tank well alone.

I also had a zebra knife (purchased as Gymnotus sp?) which even at about 15cm was a nightmare, attacking and killing loads of the other fish in the tank, including adult Angels. So back to the lfs it went!