I enjoy culturing phyto and I find it straightforward. I have been doing this for years and I rarely lose an algal strain. I wanted to share my methods with people willing to give algal culture a try.
WHY
This used to be simple to answer;larval fish feed on zooplankton, and zooplankton feeds on phytoplankton. So anybody attempting to raise fish
larvae needs to master the first two levels of the food chain, .
i.e. to rear clownfish, you need to culture phyto to feed the rotifers that you offer to the clown
larvae.
Microscopic algae are also the perfect food for growing Artemia to adulthood, and for filter feeding invertebrates.
Phyto is also needed for the "
green water technique", a popular tool in marine culturists' hands, where the larval water is kept a light shade of green by the periodic addition of algae.
But with the recent advent of frozen algae pastes,it is not clear if there remains any actual reason why we should keep culturing live algae.
A typical clownfish breeder, for instance, can perfectly grow rotifers on paste and even use it as "
green water" in the larval tanks. This is unexpected, as dead algal cells can not consume ammonia or CO2, one of the hypotheses on how
green water works. It actually contributes to the build-up of both molecules thru the cells break-down.
IMO, the need of live algae remains for culturing more delicate
larvae and zooplankters,such as calanoid copepods.
WHICH
The two most popular, easier to culture, and useful are:
Nannochloropsis (
NAN),
aka Japanese Chlorella, not to be confused whith the similar looking and named (but unrelated)
Nannochloris, and the Tahitian strain of
Isochrysis (
T-ISO). Third in the ranking would be
Tetraselmis (
TET).
NAN is the best alga for rotifers and high in
EPA;
T-ISO is high in
DHA. So a blend of both in different proportions is usually advised for larval rearing.
TET is also nutritionally sound and is said to have antibacterial functions.
I culture other species, such as
Pavlova,
Rhodomonas, and the diatom
Chaetoceros for special applications, but they are more difficult to keep.
HOW
I culture my algae under natural light. In winter I keep them in a clear roof deck room, formerly used to grow orchids. Minimum temperatures are set at 13º or 18ºC, depending on the needs, and mantained with a gas heater.
In summer it gets too warm in there and I set the cultures outside, protected from the rain and direct sun.
I use freshly mixed
ASW, at 1.010 SG, fertilized with f/2 from
FAF. Silicate is added when diatoms are cultured. I keep stock cultures in 100 ml Ehrlenmayer flasks,and according to needs, I upgrade into
2L soda bottles or
10 L bags.
Flasks
Stock cultures are kept pure and possibly sterile in flasks. Each flask is filled with 60 ml of medium, cotton stopped and sterilized in the microwave oven. When cool, 10 ml of a thriving culture is seeded with a sterile pipette.
I keep three flasks for each algal species; old, medium and new. I seed new cultures 2-3 times per month, so this is not too much work. Every morning I agitate the cultures by swirling.
I need to keep stock cultures because it is very difficult to obtain them here. In places where they can be easily replaced when lost, one can do without them.
Bottles.
2L clear soda bottles are seeded with algae from another bottle or from one of the stock flasks.Then it is filled up with medium sterilized overnight with bleach, 1.5ml/
6L and dechlorinated with thiosulphate. One small dedicated air pump is used for each bottle, with a rigid airline, so that bubbling is fairly strong.
A bottle reachs peak growth in 10-14 days and it is then harvested.
Bags.
When larger volumes are needed, I use
10L plastic bags,hanging from a
PVC structure as shown in
FAF catalog. Otherwise use of them is similar to the bottles.