Panther Grouper

Polka Dot Grouper, Barramundi Cod,
Humpback Grouper

For some aquarists, the juvenile polka dotted Panther Grouper was the reason they got into the saltwater hobby!  And yes, “Spot” was the most popular name!

As a juvenile, the Panther Grouper is a comical swimming fish with oversized fins, and has a white body with larger black dots. Their white coloring has an almost iridescent quality to it under certain lighting.  Their adult coloring is a dull white to a greenish white with smaller black dots and develop a darker mottled background pattern when stressed due to poor water quality.  The fins are pale bluish gray to greenish white with blue edging.  The Panther Grouper grows very quickly, at the rate of several inches per month when young.  They have rounded fins and their dorsal fin has pointed spines in front and is rounded on the back half.  In the wild, they grow to 27.6” (70 cm), although most grow to 20” in captivity.  Groupers are known to live from 9 to 37 in the wild, possibly longer in captivity with proper care.  They are a great beginner’s fish with the correct tank size.

The Panther Grouper is the only fish in the Cromileptes genus so far.  They often swim head down with their large pectoral fins constantly undulating as they move around looking for food.  They also learn to identify the human that feeds them and will perform for food when their human walks into the room.  Many people who have these fish relate that they are very intelligent, often allowing the owner to “pet” them.  The Panther Grouper has been seen in Florida waters, where they are not native.  They may become a threat, similar to Lion Fish who were dumped in Florida waters years ago, and who are now breeding and spreading throughout the Gulf of Mexico.  Florida is now holding “Pet Amnesty Days” where fish owners can turn their unwanted pets to qualified adopters without being charged.    

The first challenge an aquarist faces when keeping a Panther Grouper is the large tank size, which is necessary for these deep bodied fish.  The second challenge would be filtration, since groupers are big eaters and produce copious amounts of waste.  This requires a good quality oversized skimmer and two canister filters like Eheim or Fluval.  The canister filters should be cleaned twice as often as the directions suggest in order to keep them working effectively.  The third and final challenge are the tank mates that can be kept with this large fish.  Tank mate selection is not as limited compared to larger mouthed groupers, since their mouth does not open quite as wide.  The Panther Grouper is relatively peaceful, ignoring anything in the tank that does not fit in it’s mouth and not added after they were.    

The Panther Grouper can be kept with each other and with other hinds and groupers if they are added at the same time as juveniles.  Tank mates that are deep bodied and/or whose depth (top to bottom of the fish) is bigger than the Panther Groupers mouth are best.  If attempting to keep with cleaner shrimp from the Lysmata or Stenopus genus, add them first.  Groupers may still possibly eat these shrimp if they are not well fed.  Panther Groupers need to be the last fish added to an aggressive community tank since they have been known to attack fish that were added after they were, even if the grouper is not full grown.  Individuals vary in this regard, with some aquarists having no problems adding other fish and other aquarists having their Panther Grouper obliterate a fish they added after it.  Putting up a plexiglass divider before adding fish after this grouper is a great idea to see how your Panther Grouper will react.  

The aquarium should be at least 180 gallons, though 250 gallons is probably more reasonable for a full grown Panther Grouper. The configuration of the tank can be shallow or deep, reef or fish only.  Provide at least two caves or sheltered areas in which the Panther Grouper can hide at night as well as an open area for them to swim since they are more active than some groupers.  More caves or ledges are needed if there are other groupers. Live rock will help provide the biological filtration, yet it will need help from a strong skimmer and two efficient canister filters.  Water movement and light are not as important as offering them a varied diet of crustacean and fish flesh from saltwater sources, not freshwater fish flesh, since this will cause disease.  Feed them several times a day as very small juveniles, then once a day as adolescents, and only 2 to 3 times a week to satiety as adults.  At times they will rest on the bottom of the tank.

For more Information on keeping this fish see:
Guide to a Happy, Healthy Marine Aquarium

Habitat: Distribution / Background

The Panther Grouper, Cromileptes altivelis, was first described by Valenciennes in 1828..  The common names this fish is known by are High-Finned Grouper, Humpback Rock-Cod, Humpback Grouper, Humpback Seabass, Humpbacked Cod, Panther Grouper, Pantherfish, Plum Pudding Cod, Polka Dot Code, Polka-Dot Grouper, Red Fish, Seabass, Groper, and Flatfish Grouper.  The name “cod” which is common in Australia has no bearing on the relationship to cold water cods that are commonly found in the grocery store.  Most of the names have to do with shape and coloring.  Notes: The genus name Cromileptes may be changed to Chromileptes.

Distribution - Habitat:
The Panther Grouper is found in the Western Pacific from southern Japan to Palau, Guam, New Caledonia and the southern part of Queensland, Australia.  It is also found in the Indian Ocean from the Nicobar Islands to Broom, Australia.  Sightings were reported in Kenya.  Those seen in Hawaii and in the tropical Atlantic around Florida, USA were more than likely released pet fish.  Panther Groupers are found in quieter waters, in dead or silty coastal reefs, though they also can be found where there is healthy coral growth in lagoons, reef flats, reef faces and fore-reef slopes.  In Australia, they are found in lagoons and back-reef zones.  The depths they are found in are as shallow as 16” (juveniles typically found in shallow tide pools), up to 131 feet (0.4 to 40 m).  Foods most common consumed are fish that can fit in their mouths, and crabs, shrimp and other crustaceans and squid.

Juveniles are found alone in fringing coastal reefs among macro-algae, coral heads, sponges, and branching corals.  Adults are found alone or in small groups.  Panther Grouper adults are heavily hunted as game food, especially in Asian markets and juveniles are collected for the aquarium trade. 

The Panther Grouper is listed as Vulnerable on the IUCN Red List for Endangered Species, with a decreasing population. 

Similar Fish:

• Coral Grouper (Epinephelus corallicola) - Named for the area it inhabits, this grouper is white with greeish white mottling, has huge pectoral fins and is similar in every way to the Panther Grouper, except, it does not have a small compress head and has a more uniform head like other groupers.   

• Scientific Name:
• Social Grouping: Varies - Can be kept alone, or in a 300 gallon PLUS, they can be housed together if added together and last as small juveniles.
• IUCN Red List: VU - Vulnerable - Vulnerable with decreasing population trend.

Description

The Panther Grouper is one of the most recognizable saltwater fish in the hobby!  As juveniles they are a bright pearl white with large black spots.  In certain light, their white body will have an iridescent quality about it, reflecting blues and yellows.  Adults are more of a dirty white to greenish white and have around 9 dusky blotches on the body, which become more intense if the water quality is low, such as depressed pH levels.  Adults have smaller black dots than juveniles.  The dots are closer together on the head area than the body, and their fins have a pale grayish blue to greenish gray hue to them with the tips being blue in some lighting.  The body is very deep, but the head area is compressed into an almost flat shape, making for an extreme hump back appearance as the body transitions to the head.  The dorsal fin has pointed rays on the front half but appears round and smooth on the back half.  All fins are very rounded and almost oversized, including their giant pectoral fins.  The fish swims nose down most of the time with the pectoral fins constantly undulating.  They can reach 27.6”” (70 cm), yet owners report they grow to about 20” (50 cm) in captivity.  Groupers are known to live from 9 to 37 in the wild, possibly longer in captivity with proper care. 

• Size of fish - inches: 27.0 inches (68.58 cm) - 27.6” (70 cm) In captivity, they usually grow to 20” (50 cm)
• Lifespan: 37 years - Groupers live from 9 to 37 years in the wild.

Fish Keeping Difficulty

Panther Grouper juveniles are slightly less hardy as adults.  As they grow, they become more “bullet proof.”  This is not a problem for most people, since a little 2” Panther Grouper juvenile will do well in their 180 gallon tank since the water quality will be better just based on the sheer volume of the tank.  Some websites suggest the tank needs to be 250 gallons, especially if you are considering more than one grouper.  This higher water volume will help keep up the water quality.  A 20” to 27.6” grouper is a much bigger fish and needs more water volume than say an eel that is the same length.  They are not messy eaters, but do consume large amounts of food and are big poopers!  The tank should have a heavy duty skimmer and two external canister filters that are cleaned often, due to the large amount of waste this fish produces.  Although some individuals may need live foods to elicit a feeding response, aquarists can easily switch them over to prepared foods.  Feeding groupers fresh water fish will cause health issues if continued for too long.  Panther Groupers can be housed together in very large tanks that are at least 300 gallons.  They will also be fine with other groupers, as long as the tank is large enough, and they added at the same time as juveniles.  Arrange the live rock in a way that they have open areas to swim, since they move around more than most groupers.  Also, provide 2 hiding area such as caves or ledges for them to take refuge in, since they rest several times throughout the day.  

• Aquarium Hardiness: Very Hardy - As juveniles they are less hardy and need better water quality and numerous feedings a day.
• Aquarist Experience Level: Beginner - Aquarist needs a tank that is 180 to 250 gallons.

Foods and Feeding

The Panther Grouper is a carnivore.  If an individual will not eat, offer feeder fish or ghost shrimp for a short time.  Do not feed freshwater fish or shrimp after they are eating other foods, since freshwater fish and shrimp cause fatty liver disease to saltwater fish and do not have the proper nutrients. Once they are eating, quickly switch over to prepared foods such as freeze dried or frozen krill, silversides, mysid shrimp and saltwater fish flesh.  Few will accept pellets, and those should be fed occasionally.  Also, offer a varied diet of crustacean, scallop and fish flesh from saltwater sources, which can be obtained from the grocery store.  It has been noted that they seem to like raw chunks of prawn.  Feed very small juveniles several times a day, average sized juveniles twice a day, adolescents once a day and eventually feed adults 2 to 3 times a week until full.  Higher temperatures will make for a hungrier grouper.

• Diet Type: Carnivore - Do not feed fresh water fish or shrimp for more than it takes to get them eating regular frozen and prepared foods.
• Flake Food: Occasionally - Juveniles will sometimes eat flake food for carnivores.
• Tablet / Pellet: Occasionally - Sinking pellets for carnivores, though few will accept them.
• Live foods (fishes, shrimps, worms): Some of Diet - Do not feed freshwater fish or shrimp since freshwater sources cause fatty liver disease to saltwater fish and do not have the proper nutrients.
• Meaty Food: All of Diet - Offer a varied diet of different crustacean and fish flesh from saltwater sources.
• Feeding Frequency: Daily - Juveniles several times a day, adolescents once a day and adults 2 to 3 times a week until full.

Aquarium Care

Groupers are hardy and fairly easy to keep, although they do need good filtration.  Live rock and a strong skimmer are a start.  Two good canister filters like Eheim that can be cleaned regularly, not every 3 or 4 months but bi-weekly to monthly to stay effective. They do well when provided good water conditions and a well maintained tank. Guidelines for water changes with different types and sizes of aquariums are:

• Fish only tanks:

• • Large Tanks 100 gallons and over, once water is aged and stable can be changed 20% to 30% every 6 weeks depending on bioload.

• Reef tanks:

• • Large Tanks 100 gallons and over, once water is aged and stable can be changed 10% bi-weekly to 20% monthly, depending on bioload.
  •  

For more information on maintaining a saltwater aquarium see: Saltwater Aquarium Basics: Maintenance. A reef tank will require specialized filtration and lighting equipment. Learn more about reef keeping see: Mini Reef Aquarium Basics.

Water Changes: Bi-weekly - Standard maintenance is bi-weekly water changes of 15% every 2 weeks or 30% a month. If there are corals in the tank then 5% weekly to 15% every 2 weeks, depending on the tank size.

• Water Changes: Bi-weekly

Aquarium Setup

In a 180 gallon tank (681 liters), though most suggest 250 gallons, arrange live rock so there is an open swimming area.  Also form a few overhangs or caves for them to retreat to or rest near.  As the Panther Grouper grows, resize their hiding places, and as an adult, provide at least two places for them to hide.  Each grouper in the tank will need a few places to hide to help tone down aggression.  The Panther Grouper is not picky about substrate or lighting.  Keep the water at a stable temperature, which can be 72˚F to 81˚F (22˚ to 27˚C) .  Normal seawater salinity around 1.023 and normal pH between 8.0 to 8.4 is preferred.  Panther Groupers were artificially induced to spawn in captivity but the young died within a week.  They prefer the bottom area of the tank. 

• Minimum Tank Size: 180 gal (681 L) - 180 gallons (681 liters) though some suggest 250 gallons.
• Suitable for Nano Tank: No
• Live Rock Requirement: Typical Plus Hiding Places - Provide an open area to swim and a few caves or ledges to retreat to.
• Substrate Type: Any
• Lighting Needs: Any - If keeping corals, provide light for the corals needs.
• Temperature: 72.0 to 81.0° F (22.2 to 27.2° C) - 72˚ F (22˚ C) 81˚ F (27˚ C)
• Specific gravity: 1.023-1.025 SG
• Range ph: 8.0-8.4 - Suppressed or low pH will cause illness and dark mottling of color in your Panther Grouper.
• Brackish: No
• Water Movement: Any
• Water Region: Bottom

Social Behaviors

Panther Groupers are also found alone or in small groups and are generally tolerant of each other if the tank is at least 300 gallons.  They will ignore other groupers if both are added at the same time as juveniles.  Arrange the live rock to give them an open swimming area, as well as hiding places.

Any fish that fit into their mouths will be eaten.  That being said, there are more fish that will be compatible with the Panther Grouper than larger groupers with gapping jaws!  While many groupers can swallow a fish that is as deep as they are and 1/3 of their body length, the Panther Grouper cannot.  Still, longer thin fish that are the same length as deep bodied fish will be eaten if they can fit into the Panther Groupers mouth.  Larger wrasses such as Thallasoma, larger Halichoeres, and a male Bird Wrasse will be fine as long as they are adult size before adding the Panther Grouper which can grow faster than other juvenile fish.  Larger angelfish, less aggressive triggerfish, tangs, less aggressive pufferfish and lionfish are all good tank mates.  Some of the very large deep bodied damselfish that are at least 7” should be safe, as long as the damselfish is not too aggressive toward the Panther Grouper.  The only time the Panther Grouper becomes a threat, is if it is full grown and these other fish are not, and they fit in their mouth!  Add the Panther Grouper as the last fish into an aggressive reef (with no crustaceans) or fish only tank.

Panther Groupers will not bother corals.  Corals will fail to thrive, however, if the water quality drops.  This is very common once the grouper is full grown and there is not sufficient filtration.  Soft corals are more tolerant of less than optimum water quality, but SPS and most LPS are not.  Figure out what kind of water quality you can maintain and only buy corals that are not picky.

Starfish are safe, but snails, shrimp, and crabs will be eaten.  If you want to keep the cleaner shrimp that are often found cleaning the grouper, such as the Lysmata species or the Stenopus species, add the shrimp first and make sure the fish is well fed. 

• Venomous: No
• Temperament: Large Aggressive - Predatory - Panther Groupers are actually quite peaceful for a grouper, only becoming a threat to who they can swallow whole and fish added after they are established.
• Compatible with:
  • Same species - conspecifics: Sometimes - Tank needs to be at least 300 gallons, added as juveniles at the same time, and multiple places for them to hide
  • Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Threat
  • Semi-Aggressive (anthias, clownfish, dwarf angels): Threat
  • Aggressive (dottybacks, 6-line & 8-line wrasse, damselfish): Monitor - Very large deep bodied damselfish over 9.”
  • Large Semi-Aggressive (tangs, large angels, large wrasses): Safe - These fish should be adults before adding the Panther Grouper.
  • Large Aggressive, Predatory (lionfish, groupers, soapfish): Safe
  • Slow Swimmers & Eaters (seahorses, pipefish, mandarins): Threat
  • Anemones: Monitor - Water quality must be kept up to keep these creatures healthy.
  • Mushroom Anemones - Corallimorphs: Monitor - Water quality must be kept up to keep these creatures healthy.
  • LPS corals: Monitor - Water quality must be kept up to keep these creatures healthy.
  • SPS corals: Threat - Water quality must be excellent for these corals.
  • Gorgonians, Sea Fans: Monitor - Water quality must be kept up to keep these creatures healthy.
  • Leather Corals: Monitor - Water quality should be monitored.
  • Soft Corals (xenias, tree corals): Monitor - Water quality should be monitored.
  • Star Polyps, Organ Pipe Coral: Monitor - Water quality should be monitored.
  • Zoanthids - Button Polyps, Sea Mats: Monitor - Water quality should be monitored.
  • Sponges, Tunicates: Monitor - Water quality should be monitored.
  • Shrimps, Crabs, Snails: Threat
  • Starfish: Safe
  • Feather Dusters, Bristle Worms, Flatworms: Safe
  • Clams, Scallops, Oysters: Monitor - Water quality should be monitored.
  • Copepods, Amphipods, Mini Brittle Stars: Safe

Sex: Sexual differences

Males are larger than females.

Breeding / Reproduction

The Panther Groupers are born female and some become males.  This orientation is called protogynous hermaphrodites.  Unlike clownfish, hawkfish and many others, many females do not change to male just because the alpha male of the group dies or leaves.  Age, not size determines when sex change occurs.  Similar to other groupers their harems probably consist of one male and up to six females, with the male’s territory encompassing all the territories of the females.  When spawning, the male and four or five females will darken the coloring of their bodies. This starts at dusk, with a peak in spawning happening at the new or full moon.  Males will spawn with each of the females in the same night, with both releasing their gametes into the water column.  The eggs are spherical and can number from several thousand to over a million eggs depending on the size of the female.

Panther Groupers were artificially induced to spawn, yet the young only lived for one week.  

• Ease of Breeding: Difficult - Has been attempted unsuccessfully.

Fish Diseases

Though juvenile Panther Groupers need more care and are not as hardy as adults, they are still relatively hearty fish.  Adult groupers are extremely hardy, but do tend to come in with multiple parasites.  A culture was done on wild-caught groupers and there were 11 to 16 different species of parasites found on their bodies, including nematodes and cryptocaryon.  Quarantining a grouper is absolutely necessary.  Happily, the grouper will respond to treatments for any parasites they are carrying.   

The most easily cured parasite is Crypt (salt water Ich), but they are all treatable if caught in a timely manner. Marine Velvet is a parasitic skin flagellate and one of the most common maladies experienced in the marine aquarium.  It is a fast moving that primarily it infects the gills.  Then there is Brooklynella, which kills within 30 hours, however, an even nastier killer is Uronema, which will kill fish overnight!   Uronema is often contracted when the aquarist doesn’t lower their salinity to the proper level of 1.009.  The Uronema parasite thrives in mid-level brackish water salinity, which is a specific gravity of around 1.013 to 1.020.  Treat for any illness at a normal salinity with a specific gravity of about 1.023 if the fish cannot handle low salinity, otherwise, lower the salinity to exactly 1.009, no less, no more.  Quick Cure and other 37% Formalin products will work perfectly well in both salinity ranges, but the lower 1.009 will help with the oxygen level. The amount of oxygen in the water increase as the salinity level is reduced.   

Anything you add to your tank from another system that has not been properly cleaned or quarantined, including live rock, corals, equipment and fish can introduce diseases.  A few other ways to proactively prevent disease are to provide quality foods, clean good quality water, and proper tank mates. 

For information about saltwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.

Availability

Panther Groupers are seasonal and are moderately priced according to size.

References

Animal-World References - Marine Fish

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Derek Melton - 2013-02-07 I have a grouper I just purchased. It's pink and it is not doing well. I have a 150 gallon tank. I noticed today it has a weird white mossy looking stuff growing on him and it's not swimming just laying in sand opening and closing its mouth. Help I like the fish just want to get him right. Anonymous - 2013-02-08 White mossy stuff sounds like a fungus of some kind. Get a medication designed for fungus. It can't hurt to also use an anti-biotic as long as you check for ammonia and keep it down with Amquel if it rises. Gasping may be a sign of low oxygen, increase aeration or surface water flow. Gasping, or opening and closing it's mouth, may be normal though. Reply

Dian - 2010-10-27 My panther grouper is about 7 years old now. Over the last couple of weeks he kind of stopped eating, he now seems to be in a stuck position of being bend kind of sideways. He can maneuver about and all fins are working fine - other than being stuck in this position he is kind of o.k. - but is probably ill - Parasite? I know he is old, but how long do they live in captivity? He has been a special pet to me - like a dog in a fish tank, does anyone know if there is anything I can do - or do you think it is time? CosmicOps - 2012-10-31 Well it can't be swim bladder disorder, since groupers don't have one. It could be some kidney disorder caused by improper (long term) salinity:if you have the (bad) habit of keeping your fish at 1,021 to 1,023. Most Groupers can live several decades. As a rule of thumb: keep your fish only tank at the same salinity as reef tanks, 1,025-1,026 should be fine. Of course small or crowded tanks may please the keeper but prove to be lethal to the inhabitants. There should be less excentrism and more responsability in the hobby (which applies to all). Of course your grouper could also encounter liver damage caused (amongst other things) by a blood worm diet or other. Blood worms are considered to cause fatty degeneration in fish's liver. So any food with a fatty concentration should be avoided. Good Luck!! Jeremy Roche - 2012-10-31 Have water conditions changed at all?   Maybe try feeding dried krill with tongs?  Added any new tankmates in the past couple weeks?? Reply

some fish lover! - 2009-10-24 I have a panther grouper with a pink-tailed triggerfish, a clown triggerfish, a picasso triggerfish, and a yellow tang and they get along fine. I have them in a 30 gallon tank and they hardly ever fight. I love mine so you should to! mike - 2010-06-14 I had a panther grouper with a blue trigger and he has bit all the top fin off and I had to pull it out to die rather than let him eat it as he kept rolling on top of it shame in a 33 gallon tank. CosmicOps - 2012-10-31 Great News... However they are all huge fish (15 to 50 inches). You should encompass the idea of setting up a 200 gallon tank... minimum... (no joke). Man would they ever be happy! Jeremy Roche - 2012-10-31 Do yourself a favor and get a much larger tank.  These fish will get very large.  They may not be fighting but they will not be able to be maintained for long. Reply

Andrew - 2012-03-16 Had mine for six months in my 120 gal. It grew fast! Bought it around 4 inches and now it's reaching 8inches! However if you want to get one of these beauty, try to get him last. This is a semi-aggressive/territorial fish and it will chase, nip and swallow any fish it can fit in its mouth. Otherwise the panther grouper is a moderately hardy fish and great for FOWLR system! Reply

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