Black Widow Anemone or rose bta

Black Widow Anemone And Rose BTA?

Both the black widow anemone and the rose bubble tip anemone are rare and vibrantly colored sea anemones that are often mistaken for each other. Their diets and dispositions are very similar. However, they do have a few differences, the two main ones being their color and their rarity.

Black Widow Anemones are very difficult to obtain and are quite expensive as far as anemones go, while rose bubble tip anemones reproduce quickly and are more widely available. 

The rest of this article will tell you all you need to know about these two vibrant anemones – how to care for them, what they need to thrive in your tank, and how to tell the difference between them. 

What is a Black Widow Anemone? 

A black widow anemone, called by some as the crown of thorns anemone, is a rare species of semi-aggressive anemone with a dark center, which ranges from deep blue to indigo, and bright red tentacles. The tentacles fade from dark to greenish as they extend beyond the oral disc, with the latter half of the tentacles a vivid bright red. 

They often have vibrant speckles on the tentacles and a pattern that resembles white webbing near the oral disc, which attributes to the name. 

The black widow anemone prefers a moderate water flow and thrives in gentle waters. 

What is a Rose Bubble Tip Anemone?

A rose bubble tip anemone (BTA) is a rare color morph of the bubble tip anemone. As the name suggests, this anemone is a gentle dusty rose color, with plump bubbled tentacles. 

The rose bubble tip anemone is a great anemone to add to your tank if you have clownfish. In fact, this anemone will thrive with clownfish more than with other fish species, because clownfish feed the anemone bits of food. 

The rose BTA doesn’t wander around the tank like other anemone species, preferring to anchor itself to one spot – usually a rock instead of the sand. Moving any anemone once it is anchored is a bad idea, as many anemones have died from a broken column.

If your rose BTA anchors itself too close to corals or live plants, be prepared to move the corals or plants, so your anemone can be comfortable. 

How can you Tell a Black Widow Anemone from a Rose BTA?

There are two main differences between the black widow anemone and the rose bubble tip anemone: color and rarity. 


The black widow anemone has a dark center, usually dark blue or indigo. There is usually a pattern that resembles white webbing near the oral disc, giving it a characteristic spiderweb appearance that has influenced its name. Their bubbled tips are usually speckled. 

Their coloration makes them highly sought after by anemone enthusiasts, and black widow anemones are always in high demand. 

The rose BTA, while also a bubble tip anemone and is similar in size to the black widow anemone, is a light rose color with a pale purplish or pink center. It has fuller and plumper bubble tips than the black widow anemone, which has subtler bubble tips mixed with elongated tentacles. 


Black widow anemones are difficult to come by and fetch a high price tag. They are highly prized by aquarium enthusiasts and breeders because they are relatively easy to cultivate inside an aquarium, as opposed to other rare and exotic anemone species. 

Rose bubble tip anemones reproduce quickly and, as a result, are more readily available for those seeking to add them to their aquarium. While rose BTAs are also in high demand, their availability makes their price lower than the rarer black widow anemone. 

What are Bubble Tip Anemones?

The term “bubble tip” pertains to a group of perhaps 14 species of sea anemone native to the tropical waters of the Indian Ocean, the Red Sea, Fiji, and Tonga. They are found in the wild, usually attached to corals, thriving in coral reefs.

Adult bubble tip anemones are solitary animals that are found in deeper waters among clownfish, while juvenile anemones occur in clusters in a shallower region of the coral reef. While adults can endure moderate water flow, juveniles are more delicate and require mild currents. 

They can be found in a wide range of colors, including combinations of pink, red, tan, blue, orange, cream, teal, and green. What sets them apart from other anemones, however, is the characteristic balloon shape at the end of their tentacles. The swelling can be round, like bubbles, or partially swollen. 

Bubble tip anemones are hardy and relatively easy to cultivate in tanks, making them a popular choice for both buyers and sellers. Bubble tip anemones are also popular for their symbiotic relationship with clownfish, which is another popular species in saltwater aquariums

Bubble tip anemones need strong light and plenty of space to thrive. 

Is a Black Widow Anemone a Bubble Tip?

Black widow anemones are indeed bubble tips, however the swelling isn’t as prominent as many other bubble tip anemones, such as the rose bta. While there are some black widow anemones with plump, round bubble tips, this isn’t the case in most instances.

In most cases, their tentacles appear in a semi-swollen state, with the majority of them having some bubbling while the rest are elongated.

The bubbling in bubble tip anemones can disappear, as is the case with any bubble tip anemone species, due to age or stress. Make sure you are properly feeding and caring for your anemone, so stress doesn’t play a role in it losing its bubble tips. 

How Big do Black Widow Anemones Get?

Young black widow anemones reach a diameter of 1 – 3 inches when fully opened. Once acclimated to a tank, they can grow quite large, over 8 inches across, and grow more crowns (known as “splitting) which can make them even bigger. As with any species, they’ll grow as long as they are happy, healthy, and have enough space.

These size specifications are true for most bubble tip anemone species, including the rose BTA.