The Brackish Tank

It’s pretty well known that Mollies can handle full saltwater, however can Platies, Guppies, and Endlers handle it too? Furthermore, I know most, if not all, Gambusia handle saltwater, though they aren’t always available.

As for cichlids, Oreochromis and other Tilapias I’ve seen in full salt in the wild, and Mayans, as well as African Cichlids online; and the Chromides of course in brackish. However, what others can? I’ve heard Blackbelts could, but not sure on anything else. Trying to find something unique to add into saltwater, but make sure it’s humane (as African Cichlids may not be humane even though they can live in saltwater).

I think I worded this sloppily, so if any clarification is needed please ask.

No worries! I caught the drift of what you are looking for. Now... to see if I can explain concisely for a change :)

Livebearers are well suited to brackish life, as a whole. The commonly sold Poecilia species - Mollies, Guppies, Endler's - can all tolerate saltwater. In the case of Guppies, really only the wild/feeder types can tolerate salt concentrations that high; for whatever reason, the fancy Guppies only tolerate about half-strength seawater (to 1.010 or so). Both of the common Gambusia species can tolerate saltwater and yes, you'll rarely see them sold (though they do find their way into batches of feeder minnows at times), however if you live in the US, it's legal in many states to catch your own! That's what I have done anyways and very much love mine. Salinity tolerances of the commonly sold Poecilidae species can be found on my page at the following (link).

Lots of Cichlids have brackish tolerance too! In addition to the ones you've listed, Blue Acaras, Severums, Jack Dempseys, Texans, Jewelfish, and Kribensis are many of the commonly sold salt-tolerant species, but most are on the lower end of things. If you wanted Cichlids tolerant of full saltwater, then the Tilapias, Cuban Cichlid, and Mayan Cichlid are other options. Salinity tolerances of the common brackish-tolerant cichlids can also be found on this page of mine: (link)

Oof, so looking a bit into this, there are a LOT of fish species native to Ohio. Actually pretty neat how many different families can be found there! Brackish tolerance is largely confined to those species with a large range that touches the Eastern shore - and even then, there's not a lot that I immediately recognized as being very solidly brackish tolerance.

Most of the species that come to mind are the bigguns... Longnose and Shortnose Gar up to 1.010 or so, Alligator and Spotted Gar up to 1.023 or so, Largemouth Bass up to 1.018, and Blue Catfish up to 1.015 or so. American Eels are probably good in saltwater indefinitely. But all these species are huge and poor choices for home keeping. There are a lot of species that can tolerate up to 1.003 or 1.005, but half strength seawater is a no-no.

Western Mosquitofish are about it for the desirable species in aquarium keeping. I like Gambusia a lot, but I know a lot of people are less than enthused. Banded Killifish can handle some salinity, but definitely not half strength seawater and up. Around where we live, they inhabit the freshwater areas, Mummichogs inhabit the strong brackish to saltwater, and the two coexist in low brackish conditions.

Any personal experiences? Acclimation for them will be painfully slow and with any luck they’ll take.

I don't have any experience with Bluefin Killifish, only the closely related Lucania parva (Rainwater Killifish). That said, I have seen some scientific papers that suggest that Lucania goodei can tolerate a little bit higher than 1.005 (one paper suggested 10ppt or roughly 1.007). If your tankmates are compatible, I think it would be fairly low risk to attempt this housing.

A fun topic! It's been a long while since I've looked into this - will have to give it a further look when I'm not in the throes of Tylenol PM (I'm getting old and shoveling snow took a toll!). Here's what I know offhand.

Lepomis have a number of brackish tolerant species, but most are at the lower end. Bluegill, Green Sunfish, and Warmouths are all options around 1.005 or less; though I know Bluegill are occasionally found in saltier water (I have caught them in 1.008) I don't know if they are long term denizens or just visiting.

Redspotted in saltwater is news to me - when I last looked into the salinity tolerance of this species like 10 years ago, it was recorded in as high as 1.015, but it doesn't surprise me if it sometimes wanders into saltier territory. I wouldn't keep them in marine tanks full time though.

Bantam Sunfish are just behind the Redspotteds and can be found in 1.014 in the wild.

Most Micropterus are freshwater only, but the Largemouth can be found in as high as 1.018 in occasion. Not great aquarium fish though - big and aggressive.

Honorable mention to Bluespotted sunnies, which are the only Enneacanthus with brackish tolerance to some degree, but even then it maxes out at 1.003.

Alright, I apologize but my thoughts are going to meander all over the place here. Hopefully the information below is useful!

As far as I know, only N. taeniurus and N. aquadulcis are naturally found in brackish water in their home ranges - I double checked a dozen species on fishbase and only these two are noted as being native in such areas. I did find at least one study online which found invasive specimens of N. cyanomos breeding in the Gulf of Mexico around 1.016, so it's very likely that salinity tolerance isn't well understood/documented for this genus.

I believe in general that salinity tolerance for marine fishes is more flexible than many people believe. I wrote a little bit about hyposalinity in marine tanks a loooong time ago, but the gist of it is that it's not uncommon for commercial FOWLR tanks to be kept lower than full strength saltwater, mostly for financial reasons but there is also some evidence to suggest it might inhibit some nasty marine illnesses.

While I haven't done any additional research on the subject in years, at least then there was some success with keeping specific fish species (usually non-reef and non-Red Sea) in as low as 1.012. I'm unsure if this specific gravity was selected because it's just half strength seawater or if there was extensive testing to find that this is a practical lower limit.

Now, N. cyanomos has some brackish tolerance naturally so I think the jump down from 1.016 to 1.012, over a period of time, would probably be tolerated well enough. Would 1.010 be tolerated as well? It's really, really hard to say. Maybe. There are a number of factors such as cleanliness of the tank, temperature, hardiness of the individual, etc which could play a part. I sometimes find that individual organisms that on paper should survive brackish conditions don't do as well (java fern is one for me) and sometimes specimens can surprise you (duckweed is one that caught me off guard this year, specifically, which now thrives in one of my brackish tanks). You might find one that does great in your tank, or you might get some that are stressed out by the salinity.

I think you should be fine here. Monodactylus in general aren't really fish eaters - they have real tiny mouths - and while I might see issues with the normal Monodactylus sebae or M. argenteus, that's because they are much bigger. I think this combination works.

Hey there! I appreciate the kind words. I haven't really upkept this blog in... well. Years. My last real regular updates were in 2018; I had started this goal of writing up a caresheet for every common brackish fish and invertebrate in the trade, accomplished that, and then moved on to upkeeping TheNativeTank, where I talk about North American native fish keeping. That said - I do appreciate that people still enjoy reading the things that I've written!

If I had to guess, it all stems from the fact that most fish that need brackish water (as opposed to brackish-tolerant freshwater or marine fish, or euryhaline fish like Mollies) aren't really colorful. Since they aren't colorful, they aren't widely desired for home keeping thus fewer people breed them. Since they aren't widely bred, they aren't widely kept. And with all that in mind, since few people keep them few people are writing about them.

And it's a shame! These fish are usually hardy, behaviorally interesting, and usually quite handsome. I've found over the years I've lost interest in the "loud" colors of most commercially bred fish. I like greys and browns that have streaks or spots of color, or nice liquid silver color.

Is this Kottelati?

It'll take two parts to answer this question, so starting with the specific question asked: brackish tolerant shoaling fish that can adapt to 1.025. There are a few that come to mind...

Livebearers like Mollies and Guppies (and Mosquitofish and Pike Livebearers, not that they are often kept) are considered social fish but they really aren't; they can be kept singly or in groups equally effectively but they don't school. Still. Hard to pass up in my opinion.

The Fundulus killifishes are rarely seen in the trade but they are the tops in my books for this specific set of criteria. Schooling? Several species are. Brackish to full marine? Again yes for several species. Peaceful? Playful? Check and check. Mummichogs were specifically named for their schooling ability. I can't recommend them enough.

More commercially available are several species of brackish catfish. Best choice is the Tete Sea/Silver Shark catfish - large and peaceful, they are also active and fun. Less suitable... the rare Striped Eel Catfish (Plotosus lineatus) is a tightly schooling fish and also notable for a medically significant sting; anecdotal evidence suggests it can be fatal.

On the smaller side, there are several Blue Eyes (Psuedomugil spp) which school and handle salt water. P. signifer and P. cyanodorsalis are best choices. They are colorful, handsome fish! Unlikely to be eaten by Scats but unsure with Monos.

There are a few halfbeaks and needlefish which can meet this criteria but few are sold in stores. Zenarchopterus buffonis is one such species. They tend to need big tanks because of how inflexible they are.

One pufferfish is a maybe - the Parrot Puffer, like its smaller South American Puffer cousin, can be kept in small groups fairly successfully, but they are often bitey with other species. Finding them is a major challenge too.

I mean. I hope that's not the picture they sent you? Because that's one I took and posted here on this blog like. A decade ago.

tt

Good afternoon! It’s a Monodactylus spp - usually sold in the trade as Monos or Moonies. A brackish-to-saltwater genus, they are usually found in estuaries as young and in the ocean as adults, but in aquariums they can be kept either way. A classic pairing with Scats (Scatophagus/Selenotoca spp) since they were first introduced in the trade. Fun fact - back when these guys were (relatively) cheap and Angelfish were expensive, these were colloquially known as “Poor Man’s Angels”.

Thanks, Jasper

Shoal Grass? An interesting choice indeed (a first for me!) I assume you plan to collect it yourself? I don't know much about this species itself, but seagrasses in general need several inches of substrate (I've heard 6-8 inches or more) and very strong lighting (5 watts/gallon+) to thrive. Unsure if Shoal Grass behaves the same, but I'd start there. If you have success, I'd love to hear about it!

As a fan of both brackish and native biotopes - i am definitely a fan of the idea!

I do think Mummichogs may not be the best choice here... don't get me wrong I have 10 myself and they are fantastic fish - but they get big (my biggest was just a shade under 6 inches) and really want upwards of 55 gallons of water. The fiddler crabs on the other hand, really want more land than water space. They dont spend too much time in the water unless they feel threatened.

So as I see it, you have two options:

Focus on the mummichogs. They are great, charming fish that are pretty peaceful (if a little boisterous) and can survive a large range of salinity levels, so you have a lot of options for tankmates. From any number of minnow species, to Hogchokers, to Sunfish - all are great. Still want some fun crustacean additions? We have native shrimps that do great with them!

Lots! This is probably one of the easiest tank sizes to stock, so describing all possible options would take a long while. I'm not sure how obvious it is these days (I did it like 13 years ago before the mobile version was really a thing) but my page has a care sheet listed for all commonly available brackish species, complete with tank sizes, that might be of use. If you find a species or two you like, I'd be happy to help you with compatibility!

But just to not totally skimp on answering the question :) here's three I like:

A kribensis harem would be pretty neat! One male with 2 or 3 females could make a fun little tank - but doesn't really need to be brackish admittedly.

Go small! Bumblebee Gobies, Endlers, and one of the brackish Blue Eyes species gives a lot of action in a small space.

A paludarium set up for one of the brackish crustaceans like fiddlers or red claw crabs could be neat! I love fiddlers. But uh keep a tight lid on these escape artists.