Mixing FW electrogenic fishes   7/12/08 Hi! ??? I have a 46 gallon, bowed front tank which is planted and contains many hidey-holes (small and large). About a month ago I purchased my first elephant nose fish and his roommate of one year, a single black knife fish (I love both fish and didn't want to separate them after so long together). <Mmm, problematical... electrogenic fishes often don't "mesh" signal, personality wise> They seem to be great "friends", first sharing the same clear tube and then moving to the same cave. I've read many places that since they are both weak electrogenic fish, they may stress each other. I don't know if I'm hurting them by keeping them together or if they are just not of the norm and actually are good together. <Mmm, well... if yours are getting along... a reminder to all: the "price" of freedom? A: Constant vigilance... a good spiel for these personal-liberty-stolen times> Another quick question, I was interested in getting more elephant nose fish. I heard more then 3, but I'm not sure if a 46 gallon will comfortably house 4 elephant nose. I heard both, that it is big enough and that it is NOT big enough and? I was looking for a reliable answer. Please help! And thank you in advance! ~Rachel <I would not mix more in here... Please have a cautionary, informational read here: http://wetwebmedia.com/FWSubWebIndex/mormyrids.htm and the linked files in order, above. Bob Fenner>

African Brown Knifefish. Electrogenic fishes, comp.    1/30/07 Hi! About 2 years ago I purchased an African Brown Knifefish <... is this an Apteronotus species? S. American? Or Xenomystus? Or?> and an Elephantnose fish (Fishie and Ellie, respectively). 3 months ago I had to go out of town, so my sister took care of my fish for me. Kind of. <Oh oh> When I got back I discovered the water quality was awful. I managed to fix the water, but Ellie still passed away. I want to get another elephant nose but I've since read that these 2 types of fish tend to hate each other. Is this true? <Mmm... depends on what species the former is... but in general, a qualified yes here... Electrogenic species of fishes are best not mixed in small volumes/aquariums> These two always would play together and even slept in the same little pot, despite have numerous places to sleep separately. Should I scratch the Elephantnose plan and just get a different type of fish? <Mmm, up to you... but I would be prepared to move the newcomer if there was obvious agonistic behavior> I'd be devastated if anything happened to Fishie. The tank is 55 gallons and is being upgraded to 95 in June, if this makes a difference. <Does... the larger the "world" the more likely they... and other species will get along> Thanks so much, Amanda <Thank you for sharing. Bob Fenner>

Mixing Apteronotids and Mormyrids... not advised   6/3/06 Hello,       I recently sent an email to you guys in relation to keeping a freshwater dolphin in a 70 gallon planted discus aquarium. I received a reply of yes but forgot to add that I have a 15cm black ghost knife. I am aware that the ghost has a form of electrical field and was wondering if his and the freshwater dolphin will fight???? <Too likely, yes> I would also like any opinions on whether its possible to house 2 black ghost knives together? I would buy 2 smaller ones of the same size and house them in a large tank with plenty of logs and hiding places) Have you ever heard of anyone doing this successfully? <Yes... in very large systems of consistent low pH, alkalinity...> I just love this fish so much that I would have 20 of them if I could!!!!!  One more thing, how long will it take my black ghost to reach adult length. <A few years> thank for your time! Jarryd <Bob Fenner>

Freshwater fish electro-sense question I recently bought an elephant fish. today my girlfriend surprised me with a black ghost knife. they are both about 3in and are in a 34 gallon tank with separate very good hiding spots. will there 'electro-senses' clash? < There have been some studies on these electromagnetic fields generated by these fish but not much in the popular aquarium literature. But I am sure that they are aware of each other.> also how sensitive are they to salt? < These fish come from clean warm acidic water and have become very sensitive to salt.-Chuck> I use a little less then the recommended dose of aquarium salt(1tbsp per 5 gallon). tank also includes 6 glass cats and a blue lobster. thanks for your time. -Zac

How many types of fish produce appreciable amounts of electricity? <All told about 11 families, a few hundred species... are strongly and weakly electrogenic. Bob Fenner>