Giant Sailfin Molly
Water Conditions- pH around 8, clean water, multiple
daily feedings, Vegetable flake based diet
Behavior- Large, well behaved community fish. Very
distinctive, best in larger species only tank.
Breeding- 10-50 large fry born after 30 day gestation
Size- 3-5 inches, males will get up to 5.5 inches in
- Also see the care and maintenance page for the P. velifera
This will be a slightly longer care page,
because this is a very special fish. For many years this was a
fish I wanted to keep, and I knew it as THE iconic
livebearer, it would be just the type of fish I should
carry at Select Aquatics. Though not endangered in the wild,
they are very rare in the hobby, and becoming
more difficult to find.
However, I had long believed that you cannot get full
sized dorsals on tank raised fish (Not true), they
required salt (also not true), harder water, must be kept in a large
tank, took forever to grow out, and had short
intestines that required frequent feeding throughout the day.
in combination with nitrate intolerance that
can often the result of overfeeding. Whew! I have soft water,
had a job during the day, and never had the
confidence that I could keep them properly.
It couldn't be that difficult to keep this fish! Well, it
isn't, and you can keep it successfully with normal care that
does not have to be extreme, with a few
considerations for maintaining good water quality and
feeding. The reward of big 5 inch bull males
showing off to the ladies is well worth any effort!
This would occur generally when they are eating, or often in the
early morning. If you want to trigger a male to
show off, removing a female for a couple days, then
reintroducing here will often cause he males to show their
Granted, this isn't a beginner fish. Going in to it, you will
need a larger tank (30 for young fish, at least a
40 for a couple adults, 55 and over for more than about 2
trios), a habit of regular water changes, good
filtration and aeration, feeding at least 2x per day, water
that can be kept around 8.0, and a vegetable
based spectrum flake. (They do need protein foods, but do
prefer the bulk of their diet to be vegetable
From email discussions I have had with customers about
this fish, there are some things about this line
that are misunderstood. The male P. velifera possesses
the largest dorsal of any other livebearer. In the
past, P. velifera has been used to develop lines
of high fin fish that we have all seen in pet stores, fish
we are accustomed to seeing top out at about 2.5 - 3
These velifera are the true Giant Sailfins from the Yucatan
peninsula. The breeders maintaining this line made
every effort to breed only the largest males to the most
robust females, maintaining an exceptionally large, robust
fish. Previous to being obtained by these hobbyists, they
were originally kept at Clemson University. These are the
same line of velifera that used to be sold by Goliad farms
(We obtained them from the same breeder).
As a result of this, these are BIG fish. I have a tank here
of 2-3 inch fish that have yet to sex out!
Customers have asked me to ship them two pairs as I would a
pair of swords for a similar rate, and these
fish are simply too large. As well, with space being what it
is here, I simply do not have the room to grow out
dozens of sexed fish. So we are raising up the best
possible pairs, and 2-4 month old fish from those
pairs are the fish that are being sold.
The Actual Care
The tank: Yes, they will need a larger tank. Overall
water quality is important with this fish, so the larger
the body of water, generally, the more stable the water
quality will stay. Heavy water changes - at least 50% a
week, is certainly warranted here. I do 15% daily, and change
20% at any sign of cloudiness. That amount of
changes isn't required, but my tanks are fairly heavily
stocked, and I feed many times per day.
They also do best when
kept slightly warmer than the swords and other livebearers.
Though I have heard of these fish
tolerating up to 83, 84 degrees, they are kept here between
77 to about 81 degrees. To assist in maintaining water
quality, as warmer water reflects less oxygenation, air
driven box filters are used here, and some means to maintain
at least moderate aeration should be used.
To help with water quality, keep your setup with as few
unnecessary organics in the tank as possible - a sparse
pebble bottom (no thick gravel, and definitely no soil or
other contaminants.) I do use lots of plants here - mostly
Java Fern and Bolbitis fern, and they do not seem to bother
either of them. However, being mollies, I would keep
an eye out for their munching on more palatable fare.
As fry they are fine in a
smaller tank, and I have grown them out in 29 talls until they
are about an inch long.
From there they will go to 55s to grow out. My biggest fish
and breeders are kept in a 100 gallon. I can keep
up to 15-25 adults in the 100 gallon aquarium.
In following with the attention to water quality, be careful
not to overcrowd them. They generally bother their fry
very little, and can be quite prolific.
Also to assist in good
water quality, at least moderate light should be used to
maintain healthy plants and
stimulate bacterial activity in the water.
Lastly, I have also found that with these being as active as
they are, any use of rigid objects in the tank should be
carefully considered, particularly anything with sharp edges
or rough surfaces, as the bigger males seem prone to
scratching themselves and causing injury.
Salt - Those having kept the fish previous to me were
clear that these do not require salt, have never been exposed
to salt, and salt is never to be used with this fish. These
are the most competent fishkeepers I have ever known,
and have kept this fish for over 15 years, so keeping them without
salt is clearly done successfully, and any introduction
of salt should be carefully considered. You do not want to
raise fish accustomed to salt, that when put into water
without salt could face opportunistic disease issues they are
unable to fight off.
I have found that they respond very well to salt, and initial
acclimation to the water quality here to overcome
some clamped fins, etc., was solved by using a medicinal dose
of salt. (1 tablespoon per 5 gallons of water). All of
the fish sold from here have not been acclimated to salt, and
may never, as young fish, been exposed to salt.
But I will often use salt in the 100 gallon when any sign of
malaise is seen in any of the adult breeders, which
usually returns the tank to its healthy status within a day.
I will then let the salt be gradually removed through
If you want a truly distinctive, iconic, breathtaking fish,
this is it. But if you want big full sized males showing
off at one another in your living room, there is a certain
amount of meeting their needs and patience needed.
With the arrival of fry, it will be a few months before your
males will begin to show themselves, and that big
dorsal grows fairly quickly. However, the males could be
8-10 months plus before you will see them in their
full glory. But they are spectacular like nothing else
available in the hobby.
Greg Sage, 2016
See other Care Guides