Hatchet Fish Courting...

[karlp]

I was quite excited last night after doing a water change, because two of the common hatchets seemed to engage in what can only be described as some sort of courting ritual. It involved swimming up and down the mid-water of the tank together with their bottom fins touching (make a V shape if you look at them head on) and swimming around each other.

I've been keeping hatchets for several years in a community tank and never seen this behaviour before, so am wondering about putting some floating plants in and seeing if they'll spawn.

They're fed on flake and blood worm (I have to dangle the blood worm at the surface for them to take it and they come and grab it off the pincers - quite cool).

Anyone had this before ? and any advice.... particularly if they lay eggs. I think what I'll do is if they lay eggs is carefully transfer the floating plants with eggs to the quarantine tank with some tank water and see if I can hatch them, but no idea what they would eat, because I'm sure the fry would be tiny....

I'm going to try to get some pics...

Cheers

Karl.

 

[dwarfgourami]

No own experience but quoting from Sandford&Bailey, The Ultimate Encyclopedia of Aquarium Fish:

'C. Strigata (marbled hatchetfish) has been bred in capitivity. This requires very soft, acid water. The eggs are deposited on the roots of floating plants but some will fall to the bottom. They hatch in 24-36 hours and the fry require very small live food.'

Sandford &Bailey add: 'Just keeping the parents healthy can be a challenge, so breeding them is even more so'.

This on the marbled hatchetfish. They have nothing on Gasteropelecus sternicla (common hatchetfish), but maybe it's similar.

 

[Lateral Line]

Common Hatchets also lay their eggs amongst floating plants. As with strigata, the key really is soft acidic conditions. MAny tetras will spawn in good water conditions, but the eggs fail to hatch. This is because the Ca++ ions in the water react with the shell of the egg making it tough. The fry develop, but are not strong enough to break out of the egg shell.

 

[IovaykInD]

That's really interesting. Hatchetfish breeding in aquariums must be a pretty new thing. I've read in many books that they weren't known to breed in tanks. Some of the books were written in the 1990's, so I guess it was after that, that people began to be able to breed them. Might be because they need such soft acidic water that people haven't been able to breed them before then.

 

[Lateral Line]

My information come from a couple of advanced hobbyists here. As well as the low pH, low tds, very clean water and low light overgrowing plants and floating plants, the biggest problem seems to be conditioning. Although they will eat flake, frozen bloodworm etc., their natural diet contains a large number of small live insects which fall onto the water surface. Lengthy conditioning with copious quantities of fruit flies and mosquitoes seemed to be the catalyst.

It is not an easy thing. Water that soft is very unstable and keeping it steady and clean requires a lot of work. The food insects are also a challenge, and, as was pointed out by a mosquito "breeder", can be a real nuisance.

 

[karlp]

Common Hatchets also lay their eggs amongst floating plants. As with strigata, the key really is soft acidic conditions. MAny tetras will spawn in good water conditions, but the eggs fail to hatch. This is because the Ca++ ions in the water react with the shell of the egg making it tough. The fry develop, but are not strong enough to break out of the egg shell

Oh dear! My water is quite hard, so there's no chance of hatching eggs if they're laid.

Frustratingly I've not seen the hatchets do their courting ritual since the first time, although maybe I need to reproduce the conditions again (seemed to come immediately after a water change where I added water that was a bit cooler than the water temperature. Tank water temperature was at 26C).

They do seem to be doing very well though. There's a bit of a feeding frenzy with the frozen blood worm, I hang some blood worm from tongs at feeding time, so it just breaks the water and there's a lot of thrashing about as they all try and get it. Very cool.

 

[karlp]

Well, last night when I got home I found one of my leafy Anubias plants had uprooted and was floating at the surface (not sure when it happened, could have been during the night). Anyway, I took the plant out to trim it and to my surprise saw this:

I can only think it's Hatchett eggs ? I haven't got any other fish in the tank that lay sticky eggs on leaves. I have two killifish, but they haven't been in the the tank for about 10 days, so I can't think it can be them....

What do you reckon ? (fish in the tank are: 4 * syn. petricola, 1 * Ancistrus, 3 * whiptail catfish (juvenile), 9 * Pentazona barbs, 10 * common hatchets, 9 * Amano shrimp.

In the mean time, I've taken the plant out of the tank and set it up in the hospital tank, with tank water from the main tank and a small filter and heater. Set up the brine shirmp hatcher as well.... Very exciting