Indonesian sawtail
Prionurus chrysurus
Also known as: Indonesian sawtail tang, Yellowtail sawtail, Yellowfin sawtail, Chrysurus surgeonfish
This is a super cool, kind of uncommon Prionurus tang from Indonesia with that standout bright yellow tail and the "sawtail" plates near the tail base. In the wild it hangs around rocky reef surge zones in loose groups, and it is tied to cooler upwelled water compared to a lot of typical tropical reef fish.
The Indonesian sawtail features a streamlined body, striking yellow and blue coloration, and a distinctive sawtooth-shaped tail fin.
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Quick Facts
Size
30 cm SL
Temperament
Semi-aggressive
Difficulty
Advanced
Min Tank Size
180 gallons
Lifespan
10-15 years
Origin
Western Pacific (Indonesia, Papua New Guinea)
Diet
Herbivore-leaning omnivore - lots of marine algae/nori and spirulina-based foods, plus occasional meaty/frozen foods
Care Notes
- Give it a big, long tank with lots of open swimming room (8 ft runs are your friend) and strong, chaotic flow - these guys are built to cruise and will pace in cramped setups.
- Keep salinity steady around 1.025-1.026 and run the tank on the cooler side of reef temps (about 24-26 C / 75-79 F); they get cranky fast with swings, so top-off and a reliable heater/controller matter.
- Feed like a tang that means it: nori on a clip daily plus frequent small meals of spirulina flakes/pellets, mysis, and chopped seafood - underfeeding turns into aggression and skinny bellies.
- They pick at rock all day, so mature live rock and a little natural algae growth helps a ton; a sterile new tank usually ends in constant hunting and stress.
- Tankmates: sturdy, fast fish do best (bigger wrasses, angels, triggers with manners); skip slow, timid fish and avoid other sawtails or similar tang-shaped rivals unless the tank is huge and you add them carefully.
- Watch the tail spines when you net or handle it - use a container instead of a net if you can, because they snag and you can get cut or rip fins.
- Common headaches are HLLE and ich; clean water, strong nutrition (especially greens), and not letting nitrates/phosphates creep into the gutter keeps them looking right, and quarantine is worth the effort with this species.
- Breeding in home tanks is basically a non-event - they are pelagic spawners and you are not raising larvae in a display, so plan on a long-term display fish, not a breeding project.
Compatibility
Good Tankmates
- Other sturdy tangs in a big tank (think Kole tang, Tomini tang, or a Yellow tang) - add the sawtail last, give lots of rockwork and swim room, and expect some posturing at first
- Rabbitfish (Foxface, One-spot) - tough, generally mind-their-own-business algae pickers that can take a little attitude without turning it into WW3
- Medium to larger wrasses (like a Melanurus, Christmas, or Halichoeres types) - fast, confident swimmers that do not get bullied easily
- Bigger clownfish pairs (Maroon or Tomato clowns) - they are feisty enough to hold their space, and the sawtail usually ignores them once everyone is settled
- Dwarf angels with some backbone (Coral Beauty, Flame angel) - usually fine if the tank has lots of grazing spots and you are not cramming the aquascape
- More peaceful hawkfish or basslets (Flame hawk, Royal gramma) - they stick to their zones and do not try to out-tang a tang
Avoid
- Other sawtails or very similar surgeonfish (same genus or close lookalikes) - these are the ones that tend to trigger the worst tang-on-tang attitude, especially in anything but a huge tank
- Small shy fish that get stressed easily (firefish, small gobies, tiny cardinals) - not because the sawtail is a predator, but because it is a big, busy, pushy grazer that can harass them into hiding
- Slow, fancy-finned or mellow cruisers (banggai cardinals, longfin butterflies, some peaceful angels) - they can get outcompeted for food and intimidated by constant tang laps
Where they come from
Indonesian sawtails (Prionurus chrysurus) are Indo-Pacific surgeonfish that hang around rocky reef faces and surge zones where the water is always moving and food is mostly algae. Think: bright light, lots of oxygen, and constant grazing opportunities. That background pretty much explains why they can be picky about cramped tanks and stale water.
If you are used to smaller tangs that tolerate average flow, sawtails feel more like a "big open water" tang. They act stressed if the tank feels tight or the flow is weak.
Setting up their tank
This is an advanced fish mostly because of space and stability. You want a big, mature marine tank with room to cruise and lots of rock to pick at. They do better once the tank has been running a while and has natural algae films for them to graze between meals.
- Tank size: big footprint beats tall. Think 6 ft length territory if you want long-term success.
- Aquascape: rockwork that leaves open lanes for laps, plus a few caves to duck into at night.
- Flow: strong, messy reef-style flow. If detritus never lifts, your sawtail will look bored and the water will feel "flat" to them.
- Oxygen: aim for high gas exchange - surface agitation, strong skimming, and no dead zones.
- Maturity: a newer tank can work, but you will be feeding heavier and fighting algae swings more.
They are fast and can spook hard. Use a tight lid or mesh top. I have seen tangs launch when startled by lights clicking on or a sudden shadow.
I also like to give them a "calm corner". Even with high flow, leave one area behind rockwork where the current breaks a bit. They will use that spot to rest without having to fight the pump all day.
What to feed them
These guys are grazers first. If you feed them like a once-a-day carnivore, they get cranky and skinny in that head/shoulder area. Multiple small feedings works way better, with algae always in the rotation.
- Daily staples: nori/seaweed sheets (mix colors), spirulina-based flakes/pellets, quality herbivore blends
- Good add-ons: frozen mysis, brine with spirulina, chopped clam or shrimp as a treat, not the main diet
- Grazing help: let some natural algae grow on a rock in the sump and rotate it in (sounds goofy, works great)
- Feeding style: 2-4 smaller feedings beats one big dump
Clip placement matters. Put the nori clip where the fish feels safe eating it (not right in front of the glass with foot traffic). A shy tang that will not commit to the clip is a tang that will fade.
Watch their belly line and the area right behind the head. A healthy sawtail looks filled out and spends a lot of time picking. If it is pacing the glass and ignoring food, something is off (usually stress, tankmates, or parasites).
How they behave and who they get along with
They are active, alert, and not shy about claiming space once settled. The "sawtail" name is real: the little scalpel spines near the tail can do damage in a scuffle. Most of the time they are just busy swimming and grazing, but they do not love competition from other tangs.
- Best tankmates: bigger, confident reef fish that are not algae-grazing clones (wrasses, angels with attitude, larger anthias groups, sturdy reef-safe predators depending on your setup)
- Risky tankmates: other surgeonfish, especially similar body shapes or other Prionurus; also pushy rabbitfish can create constant food drama
- Avoid: tiny timid fish that get stressed by nonstop movement, and any fish already known to be a tang bully
If you add more than one tang, plan it like a chess move. Add the sawtail last, use an acclimation box, and have a backup plan. They can go from "fine" to "tail-blade fencing" fast.
I have had the best luck keeping tang peace by giving them constant grazing options. A tang that has to fight for the only nori clip becomes a problem. Two clips on opposite sides of the tank sounds simple, but it saves headaches.
Breeding tips
Home breeding is basically not a thing with sawtails. Like most tangs, they are pelagic spawners that release eggs into open water, and raising the larvae is a specialized project even for serious breeders. In our tanks, focus your energy on quarantine, diet, and giving them room.
If you ever see dusk "rushing" behavior (rapid swimming up into the water column), that can be tang courtship-style behavior, but it rarely goes anywhere in a typical home system.
Common problems to watch for
Most sawtail failures come from the same handful of issues: too small a tank, not enough oxygen and flow, stress from other tangs, and parasites arriving from a store system. They are not delicate, but they do not tolerate being shoved into a mediocre situation.
- Marine ich and velvet: tangs are magnets. Quarantine and observation save lives here.
- Head and lateral line erosion (HLLE): often tied to diet gaps, long-term stress, and water quality problems. More algae-based foods and stable conditions usually help.
- Starvation in disguise: they can eat aggressively for a week and still lose weight if the diet is too meaty or feedings are too infrequent.
- Aggression wounds: tail-swipe cuts and torn fins from tang disputes can get infected if water is dirty.
- Spooking and crashing: startled tangs can slam into rockwork. Give them clear swim lanes and keep lighting changes gradual if you can.
Do not gamble with a new sawtail in a display full of established tangs. Quarantine first, then introduce with an acclimation box or rearranged rockwork. A single bad night of chasing can spiral into parasites and refusal to eat.
The best "tell" that things are going well is simple: it cruises, it grazes, it looks full, and it is not picking fights. If yours spends the day glass surfing or hiding and only nibbles at food, treat that as a problem to solve early, not something it will magically grow out of.
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