Redblotch razorfish

Where they come from

Redblotch razorfish (Iniistius twistii) are Indo-Pacific sand wrasses. You mostly see them tied to sandy lagoons and rubble zones near reefs, where they can dive into the sand to sleep or vanish when spooked. That sand-diving lifestyle is basically the whole game with this fish in captivity.

Setting up their tank

This is an advanced fish because it asks for a mix of things that do not always play nicely together: open sand to bury, enough swimming room, and also a calm environment so it is not constantly launching itself into the lid.

• Tank size: I would not do one in anything under 4 feet long. Bigger is easier because they are active and spooky.
• Sand bed: give it a real sand bed, not just a dusting. A few inches of fine sand is what lets them bury without scraping themselves up.
• Lid: tight-fitting and gap-free. These can jump like a rocket, especially the first week or two.
• Flow: moderate. They like clean water but they also like having calm spots where food can settle and they can cruise without fighting a hurricane.
• Rockwork: keep rock stable and leave a big open runway of sand. I like a reef-ish scape with the front third mostly sand.

For acclimation, dim the lights and give it time. The first day mine buried almost immediately and did not show until the next afternoon. That is normal. What you do not want is constant pacing and panic-dashing into the glass - that usually means too much light, too much commotion, or aggressive tankmates.

What to feed them

They are carnivores that hunt small meaty stuff in the sand and water column. The hardest part is getting a new one eating confidently in your tank, especially if it arrives skinny.

• Best starters: live or fresh-frozen foods with smell - enriched brine shrimp, mysis, chopped prawn, clam, and blackworms (if you can source them safely).
• Once settled: quality frozen mixes, mysis, finely chopped seafood, and some will take small pellets over time.
• Feeding style: smaller portions 2-3 times a day at first. They do better when you keep food coming rather than one giant dump.

Watch the belly line. A healthy one looks filled out, not pinched behind the head. If it is burying all day and coming out thin, you may need to adjust timing. Mine learned to come out at "feeding time" once the routine was consistent.

How they behave and who they get along with

These are not mean fish, but they are bold once settled and they move constantly. The main personality trait is "skittish until they trust the tank". Sudden movements, slamming doors, hands in the tank - you will see them dive for cover or into the sand.

• Good tankmates: calm to semi-active reef fish that are not food bullies - tangs, rabbitfish, fairy/flasher wrasses (usually), smaller angels, peaceful damsels.
• Be careful with: aggressive wrasses, dottybacks, big hawkfish, and anything that will harass it when it tries to settle in.
• Avoid: very aggressive triggers and big predatory fish that will view it as a snack, plus hyper-competitive feeders that will starve it out.

Reef safety is mixed. They are not usually coral nippers, but they do dig and blast sand around. If you have fleshy LPS on the sand, expect it to get sanded. I keep my sandbed corals on small rocks or shelves so they are not in the "landing zone".

Breeding tips

Breeding at home is basically a long shot. Razorfish are wrasses and can be protogynous (female-to-male) like many wrasses, with social and size cues driving changes. In a big system with multiple individuals you may see displays, chasing, and color shifts, but getting a true spawn and raising larvae is beyond what most of us can do casually.

Common problems to watch for

• Jumping: the number one killer. Cover every opening, including around plumbing and cables.
• Not eating after import: very common. Start with smelly frozen/live foods, feed small amounts often, and keep tankmates from outcompeting it.
• Sand abrasions and infections: usually from rough substrate or constant panic-burying. Fine sand and a calmer environment help a lot.
• Parasites (ich/velvet/flukes): wrasses can crash fast. Quarantine is worth the hassle, but quarantine must include sand or a suitable container for burying so it is not stressed to death.
• Head and lateral line erosion: I see this more in fish that are underfed or kept in chronically dirty water. Keep nutrition varied and water quality steady.

If you see heavy breathing, flashing, or the fish staying pinned under the sand for days, something is off. Check aggression first, then oxygenation and temperature swings, then think parasites. With this species, waiting and hoping usually ends badly - they do not have a lot of extra body mass to burn.