Melanotaenia Praecox
The Dwarf or Neon Rainbowfish
by L.Eldridge
It was at the European Aquatic fair in 1994 that I first remember seeing
a photo of Melanotaenia praecox. I was talking to a fellow B.R.A.G.S.
member at the time, and we both agreed that this was a fish we would
both like to keep and try to breed.
Over the next eighteen months there was a few sightings of this fish in
many parts of the country, but mostly in the midlands and the north. The
price being asked for these fish would put most people off buying them.
I have heard reports of aquarists being asked between £30.00 and
£50.00 per pair. I have seen myself, a shop that was asking £50.00 for
an adult pair.
At the end of 1995 an importing friend of mine told me that he had seen
Melanotaenia praecox at a very good price, so I asked him if he would
bring some into the country next time he was at the wholesaler.
It was a cold Thursday evening in January 1996 when I recieved a
phone call to inform me that 130 young Melanotaenia praecox were
swimming around in my friend's tank. I arranged to go and see the fish
the following Monday evening, giving them time to settle down and to
make sure there were no problems with the fish. I then made a phone
call to Ian Pitts, the BRAGS member I had been talking to about the fish
in 1994, and told him where the fish were and the cost of them. He also
made arrangements to see the fish on the Monday evening.
On the Monday I arrived to see the fish as arranged, only to be told that
Ian had already been and had taken 10 fish away with him. I was still
met with the sight of 120 Melanotaenia praecox, all about 1" long
flashing their lovely neon blue sides as they moved up and down a 36"
long tank. I brought 5 fish for myself and another 20 for a local
shopkeeper, also a member of BRAGS. At the same time, I also brought
2 pairs of Melanotaenia splendida australis and a pair of Melanotaenia
splendida inornata, but these are another story.
I took the Melanotaenia praecox home and slowly mixed the water they
were transported in with the water I had in the tank set up for them
at home.This was a 12" x 10" x 10" tank filled with London tap water
which is hard with a pH of around 7.5. In the tank I had placed two
floating spawning mops, one light coloured and one dark coloured, a
bottom mop and a piece of Java moss. After 30 minutes of miximg water,
the fish were released into the tank. I then turned out the main light
in the fish room and left them to settle down.
The next morning I looked into the tank to see how the fish were doing.
I could only see four fish, one was missing. I have never found out what
happened to this fish. Maybe there were only four fish in one for the
bags instead of five or maybe one had jumped from the tank overnight.
The fish looked happy enough and when I offered them a feeding of
grindle worm it was taken very quickly. I have fed them on grindle worm,
frozen bloodworm, frozen mosquito larvae and flake food, all of which
they take eagerly.
Doing everthing the wrong way round, I then read a report on the
species in the Rainbowfish Study Group magazine, only to find out
that the fish prefer softer water than I had given them. So I threw a
handful of boiled peat into the tank, as the tank to this point had a
clear bottom to it, adding the peat showed up the colour of the fish
to its best. For anyone who has not seen a photo of the fish I will try
and explain its colour. If you have seen a photo of the fish, the colour
of the real thing is a lot better than any photo can show.
MALE: The colouration on this fish really has to be seen to be
believed. He is a very bright neon blue with blood red fins. The
body shape is the general shape for the larger Melanotaenia
species, but in a smaller version.
FEMALE: The same as the male but not quite as bright. The fins are
also a lot paler in colour and have a thin white line on the edge of
the anal fin. The female also tends to have a deeper, fuller body
than the male.
SIZE: Both the male and female reach a size of about two inches.
As my fish settled down it turned out that I had two pairs and after only
three days I found eggs in the bottom spawning mop. This was
removed along with some of the water from the tank and placed in a
small container with about three pints of water. I also added an airstone
set to just move the water through the mop. After about ten days fry
started to appear in the container, the following day more appeared,
after three days there was about twelve fry swimming around the
container. These were fed on A.P.R. (Artificial Plankton Rotifer).
Two days after the fry appeared in the container, fry also appeared in
the breeding tank alongside the parent fish. I quickly dipped a cup
into the tank and removed six or seven fry. The rest hid in the floating
mops so I had to leave them to take their chances with the adults. The
following morning I was very surprised to see that there were still fry
swimming around in the parents' tank and as they were still there that
evening. I thought I would leave them in the tank to see if the adult
fish would leave them alone or not.
After five weeks the largest fry, in with the adult fish, had reached a
size of over 1/4" and the adults were still taking no notice of them.
The largest fry of the ones that were removed from the spawning
tank were just under 1/4" long. but these were kept at a slightly
lower temperature.
At eight weeks the largest fry were almost 3/4" long and just starting to
show their adult colours. The fins on the males were beginning to show
a slight red colour and the body was starting to reflect a blue shine as
the fish turned into the light.
At 12 weeks they were 1" long and the males are in full colour and
lookong for females to spawn with. They are still in with the parent
fish but are now ready to be moved into their own tank(s).
I would class this fish as being very easy to keep and spawn, and in
time the silly price that is still being asked for them in some shops is
bound to fall to a level that reflects the ease of keeping and breeding
this fish.
The temperature in the spawning tank is between 76 and 78F. An
airline in the back corner gives the water a small amount of movement.
The fish were given a 10% water change each week. This water should
match the water in pH and hardness that is already in the spawning
tank.
The fry were first fed on A.P.R. and then moved on to newly hatched
brine shrimp, micro worms and frozed lobster eggs - all of which were
taken, not only by the fry, but also by the adults. As the fry get bigger
so should the size of the food, until at about 3/4" stage they will be
eating the same food as the parents.
As for the cost of my pair of fish, I did not mention it before, as anyone
who paid £50.00 for a pair may not have to happy, as my fish cost me
just £4.50 a pair.
B.R.A.G.S. Mag. May 1996