I will apologize in advance for being oververbose.

As indicated in the subject line, I'm looking for some ideas for what to add to a 65 gallon tank.

Some info on the tank:
36" wide x 18" deep x 25" or 26" high.
One Marineland Penguin filter (350 gph)
One 170 gph water pump with filter sponge and air
Can be very heavily aerated with the current bubble curtain, air stone, and water pump set to full air
Fairly smooth gravel substrate, mix of 1/8" to 1/4" diameter
Do not plan on live plants (bad lighting, no experience with live plants)

Water info:
My water is fairly alkaline, my 29 gallon is around 7.8 pH, the 65 gallon is measuring at 7.6 pH. I don't have tests for hardness, but being in this area, and judging from both my shower wall stains and the pH, lets assume the water is pretty hard.

The tank currently has one unusually aggressive Kribensis (4") a few plastic plants I grabbed from my established 29 gallon tank, a few artificial cave structures (one big plastic thing from petsmart, and a large old coffee mug I accidentally broke and superglued back together). Not sure it's actually a Kribensis, coloring seems off, but they were labeled as such at the store.. pretty convinced it's a variation of the genus.

As a bit of a background, I originally got two kribs for my 29 gallon community, but one of them was absolutely vicious, and cornered the other krib, and a few days after introduction and a feeding of bloodworms, was incessantly attacking the other fish as well (full speed chasing, aggressive and repeated biting, etc.). I was surprised since I've had kribs before, and none were ever that bad, plus I made a point to add plenty of caves/rocks and cover plants for the kribs. The 29 gallon had 10 zebra danios, and 6 green corys prior to the introduction of the kribs... They're all still there, although worse for the wear. I'm currently keeping an eye on them to make sure none of the nips get infected (so far they seem to be recovering and generally behaving normally, but one of the corys is flashing on occassion... they're definitely susceptible to anything right now from the stress). I know it's a bit crowded and having the corys mixed with cave dwellers may have been a mistake, but as noted below, I was going off of experience and never had trouble with it in the past. Now that the big aggressor is out, the other krib actually gets along with them just fine.

So when I got home from work early this week and saw the violent behavior persisting for over half an hour, I immediately siphoned out some water to a bucket, put the aggressive krib in there with some air, rushed to the pet store and bought the 65 gallon tank and stand. As a side note, trying to catch a kribensis is insanely difficult without removing all decorations from the tank. I put the aggressive krib in the new tank once I had it up and running (slowly balancing the water in the bucket with the new water in the tank first). I used some gravel from the existing tank, a few of the plastic plants, plus I took the "bio-wheel" in the established tank filter and put it in the filter of the new tank to hopefully keep any spikes in ammonia and nitrite down (so far so good). With the 65 gallon size, minimal feeding, and transfer of some of the items from the old tank, it's cycling but nothing so severe to make the water disastrous. I'm monitoring both tanks daily and changing water accordingly to make sure neither undergoes too much of a spike. Especially in the old tank, now that the other fish are stressed and injured from the recent experience.

So back to the question... what to get after it's done cycling at the current bio load? I was thinking (and am fairly set on) getting one red tail shark. After that I've pretty much limited myself to a small-to-medium-sized, semi-aggressive, community. Just don't know what else to add afterwards.

I really don't know much about fish tanks other than personal experience (pronounced trial and error) when I was growing up. I decided to get back into it to brighten my day through some current tough times. So I'm not clueless, but I don't know much and would definitely label myself as novice.... maybe a seasoned novice?

Thanks in advance for any input. This ended up being very lengthy, since this is also my intro to the forum. So... also, Hi!

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Fish can be cute. Just watch a bunch of happy corys in the same tank together. They're like little zoidbergs, but without the awkwardness or ineptitude... well maybe a little awkwardness and ineptitude.

I commend you for going to immediately buy a another tank (and a good sized one at that) for your super aggressive krib.

I did find this article on krib that may help you out a bit as well.

Facts about the Kribensis - Pelvicachromis Pulcher

As far as tank mates goes the article pretty much said what I was thinking. I think that the krib was in a breeding mood and became super territorial. Since it is a bottom to mid dwelling fish, mid - top level, fast swimming fish would be fantastic tank mates for it. According to the article tetras, barbs, or other chiclids would be good tank mates for your krib. Gouramis (who can also be territorial), angel fish, and other slow moving fish are not good tank mates (as stated by the article).

I have no personal experience with kribs or other chichlids, but that article goes into a fair amount of detail about how to take care of that fish and what is and isn't good for them. Before you go out and get more fish I would:

1) make sure your new tank has finished cycling
2) research more information about kribs and appropriate tank mates

I hope I helped you out a bit and welcome to the forums.

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Thanks for the article, that one provided a bit more info than I got from most. Unfortunately I'm discovering that information from sources published online and in hardcopy can vary quite a bit, making it difficult to decide on tank mates - which is why I went off of personal experience instead.

Makes sense I guess, each fish has a personality of their own too. I think from here on out, regardless of general known info about tank compatibility, it might be prudent to just watch them in store tank for a few hours to get a feel for temperament.

I hear the personality variations can be extreme with red tail sharks too, so I definitely have to pick one carefully.

Past that, I'm kind of liking the tetra idea, maybe a school of semi-aggressive tetras would look nice.

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Fish can be cute. Just watch a bunch of happy corys in the same tank together. They're like little zoidbergs, but without the awkwardness or ineptitude... well maybe a little awkwardness and ineptitude.

I personally love tetras because they are colorful and can come in many different varieties. I think that would be a good way to go for that tank. Being a schooling fish just get 5 or more of the same variety (5 neons, 8 bleeding heart, etc. . .) and you can definitely have more than one variety as well. They will be happier and harder for other fish to catch when in groups of 5+.

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i would put in a school of tiger barbs in there, they look great but can hold their own against more aggressive fish, especially in schools.

EDIT: once it's totally cycled, of course. although, tigers are hardy fish, but i still wouldn't do that to them.

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29g planted, Eheim 2215 canister, Top Fin 150w heater.

Albino Cory x 4, Guppy x 8, Oto x 3, Bolivian Ram x 2

Thanks for the tips! I like that idea, I think I'll go with a decent sized school of 5-10 to keep the top of the tank busy once it's all settled down.

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Fish can be cute. Just watch a bunch of happy corys in the same tank together. They're like little zoidbergs, but without the awkwardness or ineptitude... well maybe a little awkwardness and ineptitude.

Just as an update to the situation... one of the zebra danios in the 29 gallon succumbed to his wounds tonight ... he had an obvious bite mark around his head and was all around nipped really badly. No signs of disease, just bad injuries. Very upsetting especially since he was a very vibrant, active male... most of my zebras are female.

I started the tank on melafix to hopefully help the others recover.

On the upside, the 65 gallon is at 0 ppm ammonia, 0.25 ppm nitrite and 10 ppm nitrate. I guess moving the biowheel from the established tank filter really helped things move along there. Once it's cycled I think I'll move the other krib there from the 29 gallon first, just in case it decides to get aggressive like the other one.

Then I'll look into some tiger barbs or serpae tetra... I'm having a hard time picking between the two, although I have plenty of time to decide. Would there be a problem of having a school of each in the same tank? I don't know if tetras would conflict with barbs.

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Fish can be cute. Just watch a bunch of happy corys in the same tank together. They're like little zoidbergs, but without the awkwardness or ineptitude... well maybe a little awkwardness and ineptitude.

According to some info I read they would be fine together as long as you have a good sized school of each, 6+ basically for each type of fish.

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I have three generations (30 in total) of Kribs in with my Discus.. in a 155G. I've kept Kribs for a number of efforts and find them to be pretty good tank mates for most soft/low ph fish.(One I think of the few Africans) Barbs?.. Fin nippers... Tets?.. Neons are very fragile.. go with either black or cardinal tets.
um... caves aren't such a requirement as is territory.. Plant or decorate your tank so that here are plenty of escape hatches or line of sight blockages..Good luck with your / our pursuit and please keep us posted. Bill in Va.

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12 Tanks, 900 gallons. Discus/Angels/Malawi/Lake Victorias. Just added a 135 & 2 - 29's..

Oh.. I just reviewed my post.. saw my sig.. and have to add yet another 55G going online tomorrow.. Bill in Va.

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12 Tanks, 900 gallons. Discus/Angels/Malawi/Lake Victorias. Just added a 135 & 2 - 29's..