With their elegant fins and striking colors, angelfish are one of the most popular freshwater aquarium fish. Mollies, on the other hand, are hardy, peaceful livebearers that add movement and life to community tanks. At first glance, it may seem like angelfish and mollies would make great tankmates.
However, looks can be deceiving when it comes to fish compatibility.
If you’re short on time, here’s a quick answer to your question: angelfish generally should not be kept with mollies long-term. The main reasons are the angelfish’s predatory nature, different water parameter needs, and potential for aggression and bullying from the angelfish.
Angelfish Have a Tendency to Eat Smaller Fish
Angelfish are well-known for their predatory nature and the trouble they can potentially spell for tank mates if not supervised properly. As opportunistic predators, they will eat smaller fish that can fit into their mouths without hesitation.
This gives them an advantage over more peaceful community fish that are similar or smaller in size, like mollies.
Angelfish are opportunistic predators that will eat smaller fish that can fit in their mouths
With their sizeable mouths and sharp teeth, angelfish have a natural drive and ability to hunt smaller fish. According to aquarium experts, they commonly mistake long flowing fins of slower moving fish as prey and may attack.
While not overtly aggressive without reason, if hungry or provoked, angelfish have no issues with asserting their dominance in pursuit of a meal. This predatory behavior is deeply rooted in their wild instincts.
Mollies are relatively small, typically under 6 inches long
In comparison to the larger profile of angelfish, mollies are quite diminutive. Most mollies max out at around 3-4 inches for females, and 2-3 inches for males (source). Even breeds marketed as “giant” mollies average only 4-6 inches.
Given this more compact size, mollies can easily turn into quick snacks for a full grown angelfish. The body length, fins, and tail of mollies are well within striking range.
Adult angelfish can grow up to 6-8 inches long, giving them the size advantage over mollies
Mature angelfish are significantly longer in body than mollies, growing upwards of 6 inches quite commonly. With their elegant flowing fins they can occupy even more horizontal space, spanning nearly 8 total inches (source).
This grants them a crucial tactical edge in asserting themselves physically over mollies. The height of an adult angelfish alone can intimidate mollies and smaller fish from swimming into the upper levels of the tank.
Angelfish may nibble at mollies’ long fins, stressing them out
Even if angelfish can’t consume mollies whole, they may peck and fray their long flowing fins instead, causing safety concerns. The vibrant fins and tails of mollies can attract unwanted attention and nipping from angelfish, much like other long-finned species that struggle with fin-nipping tank mates.
At best this is simply stressful for mollies, but the worst case scenario is it can lead to infections, disease, and depleted health over time. Uneaten bits of fins pollute the tank as well. Such harassment is another reason mollies and angelfish tend not to coexist peacefully.
Angelfish and Mollies Prefer Different Water Parameters
When considering housing angelfish and mollies together, one of the most important factors is the water conditions. Angelfish and mollies prefer quite different water parameters, which can easily stress out one or both species if a suitable compromise is not met.
Angelfish thrive in slightly acidic, soft water
In their natural habitat in the Amazon River basin, angelfish live in water that tends to be quite soft and acidic. Most experts recommend keeping angelfish in water with a pH between 6.5 and 7.0 and a hardness of 2-8 dGH.
Trying to keep angelfish in very hard or alkaline water outside of this range can inhibit their growth, cause fungal infections, and shorten their lifespan.
Given their preference for softer, more acidic water, providing angelfish with an appropriately planted aquarium and driftwood or peat to release tannins can help recreate their natural environment. The experts at FishLab recommend doing 25% weekly water changes for angelfish rather than allowing nitrates or pH to fluctuate too severely.
Mollies prefer hard, alkaline water with some salt
On the other hand, mollies naturally live in brackish water habitats along coastal regions. They tend to prefer water that is moderately hard to very hard, with a higher pH between 7.5-8.5, and some aquarists even recommend adding aquarium salt to mollies’ water between 1-2 teaspoons per 5 gallons.
Trying to keep mollies in softer, more acidic water can cause their scales to deteriorate, increase the risk of fungal infections, and may inhibit the growth of fry. Providing mollies with crushed coral or chemical pH buffers can help maintain the proper hardness and alkalinity they require.
Small, frequent water changes are also ideal for stabilizing water quality.
Trying to find a compromise pH, hardness, etc. will leave both fish stressed
As you can see, angelfish and mollies prefer water chemistry at almost opposite ends of the spectrum! Attempting to find a “middle ground” between the soft/acidic parameters angelfish need and the hard/alkaline parameters mollies require will inevitably leave both species stressed and prone to disease.
While challenging, the best option is to set up two separate aquariums optimized for each species’ needs. Otherwise, choose tankmates for angelfish and mollies that better align with their respective water parameter preferences.
Angelfish Can Be Aggressive Toward Mollies
As members of the cichlid family, angelfish tend to display more aggressive territorial behaviors than other popular aquarium fish. This creates some risk factors when housing them with peaceful community fish like mollies.
Angelfish are cichlids, which tend to be more aggressive
Cichlids are notoriously aggressive compared to livebearers like mollies. They evolved in the rivers and lakes of South America, where competition over territory and resources was fierce. As a result, aggression towards tank mates is an innate behavior they exhibit in captivity as well.
They may chase away mollies from prime tank territories
Angelfish need plenty of open swimming areas and will claim certain sections of the tank. They are likely to aggressively chase mollies or other fish if they venture into these zones. Mollies may end up crowding into small areas, increasing stress.
Constant harassment from angelfish can stress mollies and compromise their health
Excessive chasing, nipping, or intimidation from the angelfish can raise mollies’ stress levels. Research by aquarium experts shows that high stress weakens mollies immunity and makes them prone to disease outbreaks. It also affects normal behaviors like feeding and reproduction.
Mollies’ long fins make them prone to nipping by aggressive tankmates
The large, vivid dorsal fins that make mollies attractive are easily damaged by aggressive fish like angelfish. Constant biting and tearing of the fins causes pain, opens wounds prone to infection, and inhibits swimming.
Options for Keeping Angelfish and Mollies Together
Keep them in a very large tank to allow for plenty of territory separation
When housing angelfish and mollies together, it’s crucial to provide them with ample space. A general rule of thumb is to have at least a 55-gallon tank for the two species. However, bigger is always better when it comes to reducing aggression and territorial disputes.
In a very large aquarium, these fish can comfortably establish their own zones and retreat when needed.
Add lots of decor and plants to break up sight lines and create visual barriers
Another great tactic is to heavily decorate the tank with caves, driftwood, rocks, and aquatic plants. This helps obstruct direct lines of sight between the angelfish and mollies, reducing confrontation.
Dense vegetation and decor act as natural barriers that allow the fish to get out of each other’s way. Some excellent plant choices include hornwort, Java fern, and Amazon swordplants.
Keep a higher mollies to angelfish ratio to disperse aggression
Mollies tend to be less aggressive than angelfish when kept together. Having a larger mollies school helps absorb and dissipate any bullying from territorial angelfish. Aim for at least 6-8 mollies to 2-3 angelfish. The more mollies, the better in terms of minimizing angelfish aggression.
This diffuses any harassment and prevents the angelfish from targeting any individual molly.
Choose very large mollies and small, peaceful angelfish varieties
Selecting the right size combinations and breeds can make cohabitation much smoother. Large mollies that are 3-4 inches long are better equipped to handle themselves against angelfish. Smaller dwarf angelfish species like the Golden angelfish are usually less aggressive and territorial.
When the size difference isn’t too drastic and breeds are naturally docile, aggression tends to be reduced.
Closely supervise them for signs of aggression or stress
Regardless of tank size or other measures, it’s essential to monitor the angelfish and mollies closely, especially during initial introduction. Look for any signs of aggression like chasing, fin nipping, or lip locking.
Also watch for symptoms of stress such as hiding, clamped fins, rapid breathing, loss of appetite or coloration. At the first sign of trouble, separate the fish and reconsider if they are compatible tankmates.
Better Tankmates for Angelfish and Mollies
For angelfish: other medium-large peaceful cichlids, smaller tetra species, Corydoras catfish
Angelfish do well with other similarly-sized peaceful fish that enjoy the same water conditions. Some great options are other medium-large cichlids like acaras, rams, and severums. Smaller schooling tetras like neon tetras, rummynose tetras, and cardinal tetras also make good tankmates as they won’t nip at the angelfish’s long fins.
On the bottom level of the tank, Corydoras catfish are an excellent choice. These small armored catfish will scavenge any leftover food from the substrate and keep things tidy. The peppered, albino, and bronze varieties are particularly nice.
For mollies: guppies, platies, swordtails, cichlids from Lake Malawi
Mollies are very social fish that do well with others that share their temperament and water parameter needs. Some top mollie tankmates are:
- Guppies
- Platies
- Swordtails
- Peaceful African cichlids like Yellow labs, Acei, and Rusty cichlids
These livebearers and African cichlids enjoy water conditions similar to mollies – moderately hard and alkaline. They are peaceful, active, and help highlight the beauty and colors of the mollies.
Avoid keeping angelfish or mollies with aggressive fish like tiger barbs
Both angelfish and mollies should be kept away from nippy or aggressive fish. Tiger barbs are particularly problematic as they are very energetic and likely to nip at the long, flowing fins of angelfish as well as stress out more peaceful mollies.
Other fish to avoid are common plecos (may suck slime coats when bigger), crayfish (may grab fins), and large aggressive cichlids like oscars and jack dempseys that may see smaller fish as food.
By choosing suitable friendly tankmates, you can ensure that both angelfish and mollies live together happily and display their best vibrant colors and behaviors!
Conclusion
While angelfish and mollies both come from Central America originally, these two fish have some important differences that make them poor long-term tankmates in most cases. The main hurdles are angelfish’s predatory tendencies, differing care needs, and potential aggression issues.
That being said, with a very large tank and careful supervision, it may be possible to keep an angelfish-mollies community together successfully. But for most aquarists, it’s better to pick tankmates that naturally align better with either angelfish or mollies for a more harmonious freshwater aquarium.
