switched foods and now goldfish is acting weird?

I have a goldfish in a 30 gallon tank and after feeding him a mix of bloodworms and flakes for a while, I've switched to medium sinking pellets because he's pretty big and I thought he might not get as much nutrients from small flakes. I usually feed him one large pinch a day.

I switched from natgeo fish flakes to omega one medium pellets. before feeding he is active very active and his fins are unclampped, but after feeding he lays at the bottom with his fins clamped doing that goldfish :0 thing. he's about 7 inches so I figured he would have no problem eating them.
I also have a small fantail(?) in the tank and she usually spits them out cause she tries to fit 3 in her mouth at a time.


old spice for scale.

the filter is a penguin bio wheel 350 suited for 75 gallon tanks. I tested the water and nitrates and nitrites are at 0, ph at 7
he is pooping fine and doesn't seem to be bloated but should I be worried about this behaviour? he's about 8 years old and I haven't seen him act like this for a long while when he was in a smaller tank
thanks



+ I bought this girl at a fish auction and she was labeled fantail which she has but she also has a slI'm body and weird dorsal fin? any ideas what she is? she's growing quite slowly compared to other goldfish I've had

 

I've had nothing but bad results with most foods except for SakI Hikari. I tried omega and one of my younger fancies ended up with swimming bladder issues which took almost 6 weeks to get her out of it.

SakI is Hikari's pro-biotic pellets which aid in better nutrition, less poop and overall healthier fish. My Fancy is almost 10 years old now and has always been fed HikarI food stuffs whether it be dry or frozen.

The second photo for me is possibly indicating a stunted growth, thus the weird body form. Some outgrow stunted growth but is rare. As long as she/he is eating, swimming about and being a happy fish I wouldn't worry too much.

 

I also wonder if the odd body form is maybe the result of a less than common breeding mix such as a comet or Shubunkin with a ranchu or other fancy fantail type to plausibly account for the more arched back of the ranchus/fantails on a sleeker body shape as the comets or Shubunkins have. If the fancy/fantailed parent in question was a ranchu that would also make sense for why the dorsal fin seems so small in proportion to the rest of the fish. That being said, I do think a deformity or stunting as Dadio mentioned looks like a much more likely culprit here.

 

I had a similar problem with my goldfish "bottom sitting" I was feeding them a wide variety of foods, solidgold pellets, medikoi, omega one pellets, spiriluna pellets, and aquadine pellets along with the occasional spinach or crushed shelled peas. I kept thinking this was a swim bladder disorder or some other ailment and only recently found the issue. My fish were constipated and lazy. There was little water flow in the tank as I had reduced it fearing it was too strong and I was feeding the fish every day. Goldfish are greedy eaters as they need to stock up on food to hibernate in the wild. In an aquarium they don't have to do hibernate and so get fat and constipated as they never shed their weight and without water flow they get lazy. I would try getting a powerhead like the hydor koralia or marineland maxijet. This acts like an underwater treadmill for the fish and has worked wonders for me. Also maybe try feeding them only 2-3X per week and feeding only crushed shelled peas for a week or so. Another thing to note, good job switching to the sinking pellets, flake food really isn't very nutritious for goldfish and they often suck in air gulping at the surface which causes swim bladder issues. You are much better off with those sinking pellets. Always try and feed your goldfish a diet high in fiber as too much protein will constipate them and lead to bottom sitting. HikarI is an excellent brand as is solid gold, and every goldfish is different, one food might work great for one and not so well for the other, (goldfish must be "pampered") but finding food high in fiber will help tremendously, as will getting an "underwater treadmill". Keep that water flowing to keep those fatties movin!

 

Sorry in advance for the long post but I think even if I am totally wrong (and I really hope I am) I wanted to get this out there.

One thing you might consider is if you have sand substrate, many goldfish owners have no problems with their goldfish throughout their entire lives but many others find that their goldfish are so greedy for food that as they try to gobble up every last pellet, they end up downing entire mouthfuls of sand with it. If they pass it without issue of if they are able to spit it all out while somehow eating ONLY the food pellet with zero sand in the process, then it doesn't cause problems. However, with sluggish digestive systems that seem endemic to goldfish and the ease that many become constipated, this is rarely the case and so it builds up in their system.

I say this out of experience and if you have sand substrate, perhaps it will serve as a warning while things are still reversible. I had 4 goldfish until about a month ago, and sand for quite awhile before I wished up but by then it was two late. Three had no problems with the sand, they were either smart enough to spit it out, or were delicate enough of an eager for the baby that he didn't get ingest it in the first place. For the the others, they were able to pass it through completely when they didn't get ALL the sand out of their mouth. The exception was the second youngest that continually picked at the sand for food even after none was left there. Whenever he got really bad with his "boyancy issues," was sitting on the bottom and not acting himself at all, I would switch to all algae disk crumbles for several days (he refused the usual fix of cooked peas) and he would be back to his normal self. Eventually though, it would always come back and seemed a little harder to get rid of each time.

I tried everything: increasing fiber in their diet, switching to a better quality food from their usual mix I use, feeding the algae disk diet for extended periods of time in case I was stopping that too soon, fasting with only Anacharis to eat, fasting entirely, even (as absolute last resorts) treating with aquarium salt in a quarantine tank for him, then when that failed, treating with meds, and he would always seem to improve for awhile before his issues would come back with a vengeance.

By the time someone asked if I was using sand substrate and explained why so many fish-keepers recommend against that in goldfish tanks, he was beyond bouncing back. I had the tank completely bare-bottomed for more than a month with no change in him whatsoever and he was clearly suffering so I finally had to euthanize him because it got to the point where he wouldn't eat, he wasn't able to swim or even keep himself oriented upright but would drift listless across the bottom when bumped by another fish that was trying to get him up and moving. I wish now that I had known early on to keep an eye out for sand ingestion and if I had, would have removed it at the first sign of any ill-effects, then perhaps he wouldn't have had to go through everything he dealt with.

While I don't want to start you panicking, I do think all goldfish owners should be aware the potential sand has of causing problems in certain individuals in the tank. Perhaps if other causes are eliminated as to why he is acting so unusual and it has continued throughout the time it takes to eliminate other options, then try putting him in a bare-bottom tank for awhile? It can't hurt to try and may just save him a lot of illness and discomfort in the process. If this is a recent development and if it really is being caused by ingestion of sand, then he will have a much better chance of bouncing back than if it was going on for months like mine did. The easiest way to test this theory is probably separate tank - even if it's a makeshift one of a big plastic storage tub with a spare filter hooked up to it - as opposed to attempting to remove all substrate from the home tank just for a test. (You can always remove the offending substrate later on if you decide you really do need to.)

 

If goldies can get it in there mouth there's always the risk. Sand, fine crushed rock or light substrates will always be an issue with them. I have small river rock pebbles and larger bottom substrate where one of my fancies is having the same issue with SB so I do believe I'm going to have to do the same.