Why Do Blue Tangs Rub Against Rocks?

Blue tangs are beautiful fish that make any coral reef tank more vibrant with colour;

However, if you’ve noticed your tang rubbing against rocks more often, then you may start to suspect some kind of parasite.

Why do blue tangs rub against rocks and is it something you should be concerned about?

Why Do Blue Tangs Rub Against Rocks?

Blue tangs do like to hide amongst the rocks, so rubbing against them to get in and out of a hiding place is normal. Constant rubbing can be a symptom of flukes, ich, or velvet.

Discerning whether your tang’s behaviour is normal or not can be difficult, but to keep your tank healthy and prevent the risk of infection, it’s worth looking into the possibility of a parasite if your tangs are rubbing against rocks.

Blue Tangs Rub Against Rocks

The rest of this article will walk you through how to spot parasites on your fish and what to do about it.

Normal Tang Behaviour

Tangs like to nestle themselves among the corals or in between rocks. Getting into tight spaces is part of how these fish would survive in the wild.

As such, if you see your tang wiggling or vibrating past some rocks to get into a tight space, you probably don’t need to worry about the possibility of infection.

Rubbing Due to Parasitic Infection

Parasitic infections like ich are common in tangs and glancing off rocks or rubbing against sharp objects is the first visible sign of parasitic infections. It is, quite simply, the fish’s way of trying to remove foreign objects from its body.

1. Ich

One of the most common infections that tangs get is ich. They are particularly susceptible to it, and if you have ich, you’ll need to treat your entire tank. If your tang has ich, you’ll notice visible white spots that are smooth and round on their body.

Treatments vary, but most fish keepers opt for a hearty dose of medication. Aquarium salt and UV lights can also help kill ich.

2. Velvet

Velvet is a deadly disease that can kill a fish very quickly. If you notice a loss of appetite, heavy breathing, or increased reclusiveness, you might start to suspect velvet. Some fish also swim directly into the flow of a powerhead, which is a symptom unique to velvet.

Visibly, you’ll see little spots of white like powdered sugar on your fish, typically located on the fins. A round of velvet-specific medication to hopefully knock out the disease.

3. Flukes

Flukes is a term for a variety of parasites that can harm fish by infecting the skin and gills. They can come in from infected corals or water. If you notice these symptoms, it’s quite possible your tang has flukes:

  • Cloudy eyes
  • Increased breathing rate
  • Torn fins
  • Abundance of mucous coating
  • Loss of appetite
  • Twitching or glancing off rocks
  • Discoloration

Treating flukes can be difficult. Some recommend a freshwater dip, but this method can be ineffective.

Setting up your tang in a quarantine tank and using medication to treat the affected fish is best for any parasitic infection, and you should always quarantine any new fish before introducing them to your tank to avoid the risk of infection.


Hello, I'm Jason. I'm the guy behind HelpUsFish.com. I volunteer at my local fish shop and I created this site to offer tips and advice on the fish I care for.

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