Columbian Shark

[DevilsRainbow]

ok, so i just got one. the people at the store failed to let me know that they like brakish water in later years. I put him in my 75 gallon tank with 2 severums, 2 silver red tailed barbs, sucker fish, and some kinda catfish.
what do i do when he gets older? is it really important to add some salt to the water? and if it is, can i add some salt with the fish i have?

also...whats their growth rate? i hear they grow fast...but what..inch or 2 in several months?

 

[tnhowery]

ok, so i just got one. the people at the store failed to let me know that they like brakish water in later years. I put him in my 75 gallon tank with 2 severums, 2 silver red tailed barbs, sucker fish, and some kinda catfish.
what do i do when he gets older? is it really important to add some salt to the water? and if it is, can i add some salt with the fish i have?

also...whats their growth rate? i hear they grow fast...but what..inch or 2 in several months?

I would call the store and open them a new one... My lfs was doing the same thing here, he bought one without knowing better. After finding out they required brackish he called the store and let em have it...Next week no more CS in stock...as for keeping them cichlids can stand the salt i think about 1tbsp. per 5 gallons of water but dont quote me on that one. As for your other fish im not sure. I would take them back if i was you.

 

[nmonks]

ok, so i just got one. the people at the store failed to let me know that they like brakish water in later years. I put him in my 75 gallon tank with 2 severums, 2 silver red tailed barbs, sucker fish, and some kinda catfish.

They don't "like" brackish water, they *need* brackish water, and they need brackish water essentially from day one. You can probably keep shark catfish in freshwater without problems for a few months, perhaps even years, but eventually you'll find your fish swimming around anxiously. Often, they start to get plagued with things like finrot. Regardless, it's obvious that the fish is trying to swim downstream, towards the sea. Unlike many other members of this family (the Ariidae) the Colombian shark catfish doesn't spend much time in the sea, and only about 50% seawater (SG 1.010) is needed for long term health. You can keep them in seawater if you want, though. It goes without saying that they are totally incompatible with your collection of freshwater fish.

what do i do when he gets older? is it really important to add some salt to the water? and if it is, can i add some salt with the fish i have?

Yes, it's important to add salt. These fish are obviously stressed when kept in freshwater constantly, and also become more prone to sickness. No, your existing fish cannot be kept in brackish water. ("Some kind catfish" could be anything... there are even catfish that live on coral reefs! So you need to be a little more specific here.)

also...whats their growth rate? i hear they grow fast...but what..inch or 2 in several months?

They grow rapidly. Expect around 15-20 cm within the first year, and full size around 25-40 cm within three years. There are likely more than one species sold under the Colombian shark catfish name, which is why estimates of the adult size is a ball park figure at best.

One last comment: these are intensely social fish. They *need* to be kept in groups. The more, the happier. They are totatlly inoffensive animals towards anything they cannot swallow whole, and adults and juvenile catfish can be mixed perfectly safely. Adults are truly spectacular catfish: they look and move like sharks, and have beautifully streamlined, obviously powerful bodies. Because they are day-active and so sociable, they are among the nicest predatory catfish available, and in my opinion one of the best species of brackish water fish available. Well worth making an effort to care for.

Cheers, Neale

 

[DevilsRainbow]

ok...i can transfer the fish in my big tank to another...i can leave the severums right? and i'll get another columbian shark friend in a couple days ^.^ one thign i need to know, how much salt to i need to add? its 75 gallon, and is there a special salt i need?

 

[nmonks]

i can leave the severums right?

Wrong. Severums need freshwater, ideally on the soft and acidic side. There are lots of brackish water cichlids, but severums aren't among them. Instead, consider things like green chromides (Etroplus suratensis) and blackchin tilapia (Sarotherodon melanotheron). Both of these will enjoy half-strength seawater (the tilapia will actually do well in full seawater).

i'll get another columbian shark friend in a couple days

Good.

one thign i need to know, how much salt to i need to add? its 75 gallon, and is there a special salt i need?

Colombian sharks will need at least 1/3rd seawater and ideally around 1/2 seawater upwards. The minimum specific gravity (SG) you should even think about is SG 1.008, which is ~12.8 grammes of marine salt mix per litre. A good SG to aim for is 1.010, which is ~15.5 grammes per litre. You cannot reliably weight out the marine salt mix, however, and will need to invest in a hydrometer (which will cost no more than $5 for a basic floating glass model). If you want to explore the relationship between SG, salinity, and the weight of salt, download my Brack Calc tool and it'll soon become clear how the whole thing works.

Oh, and yes, you do need special salt. Marine salt mix. Not cooking salt. Not tonic salt. Not "aquarium" salt for goldfish or livebearers (neither of which actually want salt, but there you go). Go visit a marine aquarium shop, and tell them you want marine salt mix for an aquarium. Instant Ocean, Red Sea, and others, they're all good. Just make sure you get a brand that's designed for marine aquaria. Beyond that, pick the cheapest.

Cheers, Neale