FILED

U.S. COURT OF APPEALS

ELEVENTH CIRCUIT

 APRIL 17, 2012

JOHN LEY

CLERK

 [DO NOT PUBLISH]

IN THE UNITED STATES COURT OF APPEALS

 FOR THE ELEVENTH CIRCUIT

 ________________________

 No. 11-12296 

 ________________________

 D.C. Docket No. 7:08-cv-00013-HL

SOUTHERN STATES COOPERATIVE, INC., 

llllllllllllllllllllllllllllllllllllllll Plaintiff - Appellee,

 versus

MELICK AQUAFEEDS, INC., 

MELICK AQUAFEED, LLC, 

llllllllllllllllllllllllllllllllllllllll Defendants - Appellants.

________________________

 Appeal from the United States District Court

 for the Middle District of Georgia

 ________________________

(April 17, 2012)

Before EDMONDSON and WILSON, Circuit Judges, and VINSON, District *

Judge. 

Honorable C. Roger Vinson, United States District Judge for the Northern District of *

Florida, sitting by designation.
PER CURIAM:

Southern States Cooperative, Inc. (“Southern States”) is a commercial

producer of tilapia with facilities in multiple states. In or around 2003, it began

buying feed from Melick Aquafeeds, Inc., and, a few years later in 2006, from

Melick Aquafeed, LLC (“Melick,” collectively). In October 2006, Southern States

noticed a decline in the growth of its tilapia and a decrease in feed consumption by

the fish. Southern States then began testing each shipment of feed to see if it

complied with Melick’s guarantees regarding fat and protein content. After

discovering that some samples of feed that were tested did not comply, Southern

States brought this suit for breach of warranty, negligent misrepresentation, and

fraud.

In preparation for trial, Southern States retained Dr. Steven Craig, a doctor

of fish nutrition, and Melick retained Dr. Donald Davis, a professor of fish

nutrition. Both parties filed motions to exclude the other’s expert testimony; both

motions were denied. During trial, Dr. Craig testified regarding the causal link

between fat and protein levels in feed and fish growth. 

At the close of evidence, Melick moved for a directed verdict on Southern

States’s claim for lost profits, but the district court stated that it would defer its

ruling until after trial. The jury then found that Melick had breached its warranty

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and awarded Southern States $770,229.30 in lost profits. Because the district

court had not ruled on the motion it had previously deferred, Melick filed a

renewed motion for judgment as a matter of law pursuant to Federal Rule of Civil

Procedure 50(b) (or a new trial) regarding damages. The district court denied that

motion. 

Melick now appeals on two grounds: (1) that the district court abused its

discretion in allowing Dr. Craig to testify regarding causation and (2) that

Southern States’s damages award is impermissible. After review and argument,

we affirm. 

I.

Melick argues that the district court erred in permitting Dr. Craig to testify

because his theories were unscientific and unreliable. We review evidentiary

rulings for abuse of discretion and may only reverse if there was substantial

prejudice to the aggrieved party. Goldsmith v. Bagby Elevator Co., 513 F.3d

1261, 1276 (11th Cir. 2008). A district court may not admit an expert opinion if

the supporting methodology for the opinion is not “‘sufficiently reliable as

determined by the sort of inquiry mandated in Daubert.[ ]’” United States v. 1

Frazier, 387 F.3d 1244, 1260 (11th Cir. 2004) (en banc) (quoting City of

 Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 589, 113 S. Ct. 2786, 2794 (1993). 1

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Tuscaloosa v. Harcros Chems., Inc., 158 F.3d 548, 562 (11th Cir. 1998)). Under

Daubert, a court evaluates the reliability of methodology by considering “(1)

whether the expert’s theory can be and has been tested; (2) whether the theory has

been subjected to peer review and publication; (3) the known or potential rate of

error of the particular scientific technique; and (4) whether the technique is

generally accepted in the scientific community.” McCorvey v. Baxter Healthcare

Corp., 298 F.3d 1253, 1256 (11th Cir. 2002) (citing Daubert, 509 U.S. at 593–94,

113 S. Ct. at 2796–98).

Dr. Craig testified to the following: Fish feed contains a mix of protein and

fat. Fat, unlike protein, induces satiety in fish. Therefore, a high fat content in

feed limits the quantity a fish can eat. If a fish were to consume a smaller quantity

of feed, that would decrease its intake of growth-inducing protein, resulting in a

depression of growth. This effect would be exacerbated if protein levels were

lower than average in the feed. In Dr. Craig’s words, “the worst possible

combination is a really high fat diet combined with a low protein diet, cause, as I

mentioned earlier[,] the fish, he eats to satisfy his energy requirement, so if he’s

got a lot of fat in that diet, he’s going to stop eating before he gets enough protein

to grow.” On appeal, Melick does not challenge the validity of this theory of

causation or the scientific methodology that supports it.

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However, Dr. Craig also testified that the fluctuations in the feed’s fat-toprotein ratios were harmful to fish. He admitted that no scientific studies have

been conducted to support his comments that variations in feed composition can

inhibit the growth of fish. Melick, arguing that this testimony about fluctuation

created prejudice, asserts: “Because plaintiff presented no other evidence of

causation, the jury had to have accepted Craig’s causation theory that the

fluctuation in protein to fat levels caused the decrease in growth in plaintiff’s

fish,” (emphases added) and juries give great weight to expert testimony. 

We cannot agree with Melick’s assertion of prejudice and its

characterization of Dr. Craig’s testimony. Mark Twain advised, “Do not tell fish

stories where the people know you; but particularly, don’t tell them where they

know the fish.” In this case, we know the fish—and the facts—and by no means

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was the “fluctuation theory,” as Melick has dubbed it, Dr. Craig’s sole (or even

primary) theory of causation. Dr. Craig only mentioned the effect of fluctuating

nutrient levels a few times in his extensive testimony, and those remarks were

independent of his main causation theory that low levels of protein and high levels

See Mark Twain: Collected Tales, Sketches, Speeches, & Essays, 1891-1910, 942 (Louis 2

J. Budd ed., Literary Classics of the United States 1992).

5
of fat can slow fish growth. Because we do not find that admission of Dr. Craig’s

testimony created substantial prejudice to Melick, we will not reverse that

evidentiary ruling. 

Melick also contends that Dr. Craig’s differential etiology was deficient. 

Differential etiology is a process of elimination in which (1) an expert compiles all

possible causes of an injury, see Hendrix ex rel. G.P. v. Evenflo Co., 609 F.3d

1183, 1195 (11th Cir. 2010), and (2) he rules out each of the potential causes

“until reaching one that cannot be ruled out or determining which of those that

cannot be excluded is the most likely,” Guinn v. AstraZeneca Pharm. LP, 602 F.3d

1245, 1253 (11th Cir. 2010) (per curiam) (citation and quotation marks omitted).

3

When ruling out causes in the second step, an expert “must provide reasons for

rejecting alternative hypotheses using scientific methods and procedures and the

elimination of those hypotheses must be founded on more than subjective beliefs

or unsupported speculation.” Hendrix, 609 F.3d at 1197 (quoting Clausen v. M/V

NEW CARISSA, 339 F.3d 1049, 1058 (9th Cir. 2003)). 

Melick argues that Dr. Craig failed to complete step two because he did not

scientifically rule out alternative causes for the slowing of fish growth, but instead

Guinn uses the term “differential diagnosis” rather than “differential etiology,” but 3

explains that it is simply following “the trend among federal courts . . . [to] use the term

differential diagnosis to refer to both concepts.” 602 F.3d at 1253 n.6. 

6
“assumed them away.” Melick contends that all of the following could have been

causes: poor water quality or temperature, changes in feed, disease, faulty

equipment, or overstocked tanks. Southern States correctly points out that Dr.

Craig addressed these factors, testifying to the following: Tilapia are hardy fish

capable of thriving in a variety of water conditions. Any problems with water

conditions are usually caused by feed—either pollution of the water because fish

have not consumed the standard amount of feed or increased ammonium levels

from improper protein content. Changes in feed only affect fish for one or two

days and then they will resume normal eating habits. Virulent bacterial strains are

the major disease affecting tilapia, but “everything will die” if bacteria afflicts a

tank. Given that the mortality rate in the tanks was low, a bacteria infection was

unlikely. Southern States employed daily monitoring procedures to examine water

quality and equipment. 

Melick labels Dr. Craig’s rationale as unscientific, but it fails to adequately

explain what deficiencies it finds in his methodology or procedures. It appears

that Melick really just disagrees with Dr. Craig’s statements; in substance, Melick

asks the court to reverse on the ground that Dr. Craig has not provided persuasive

or sufficient explanations for ruling out causes. However, the court’s role as a

gatekeeper “is not intended to supplant the adversary system or the role of the

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jury: ‘[v]igorous cross-examination, presentation of contrary evidence, and careful

instruction on the burden of proof are the traditional and appropriate means of

attacking shaky but admissible evidence.’” Allison v. McGhan Medical Corp.,

184 F.3d 1300, 1311 (11th Cir. 1999) (citing Daubert, 509 U.S. at 596, 113 S. Ct.

at 2786). Melick’s contentions speak to the weight to be afforded Dr. Craig’s

testimony, not its admissibility, and are thus not within our province to evaluate. 

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II.

Melick also challenges Southern States’s damages award. We review de

novo the district court’s denial of Melick’s motion for judgment as a matter of law

under Rule 50. Optimum Techs., Inc. v. Henkel Consumer Adhesives, Inc., 496

F.3d 1231, 1251 (11th Cir. 2007). In our review, we draw all inferences in favor

of the non-moving party. Russell v. N. Broward Hosp., 346 F.3d 1335, 1343 (11th

Cir. 2003). We “affirm the jury verdict unless there is no legal basis upon which

the jury could have found for [the plaintiff].” Telecom Technical Servs. Inc. v.

Rolm Co., 388 F.3d 820, 830 (11th Cir. 2004). 

Melick argued before the district court that Southern States had not

 Melick makes much of the fact that the district court appeared to suggest in a post-trial 4

order that its Daubert ruling with regards to Dr. Craig may have been incorrect. While there may

arguably have been some deficiencies in Dr. Craig’s assumptions and testimony (e.g., his failure

to independently test the water quality in the tanks), those issues were subject to rigorous crossexamination, were satisfactorily explained, and were properly left to the jury to consider. Any

error was harmless. 

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submitted sufficient evidence to prove its lost profits to a reasonable degree of

certainty. On appeal, Melick contends that a lost profits measure of damages is

inappropriate and that Southern States should only recover for its delay in

receiving profits. Because this delay argument was not raised below, we decline

to consider it. See BUC Int’l Corp. v. Int’l Yacht Council Ltd., 489 F.3d 1129,

1140 (11th Cir. 2007) (“As a general rule, we do not consider issues not presented

in the first instance to the trial court.”).

Melick argues in the alternative that if a lost profits measure of damages is

correct, Southern States failed to properly prove its anticipated expenses. Under

Georgia law, a plaintiff seeking recovery of lost profits must typically prove both

anticipated revenues and expenses with reasonable certainty in order to recover. 

Bennett v. Smith, 267 S.E.2d 19, 20 (Ga. 1980). If a plaintiff can show that

expenses remained essentially the same during the period at issue, the jury is

authorized to award the plaintiff its lost revenues during that period as lost profit

damages. See id. (allowing jury’s award of lost revenues as a lost profits measure

where plaintiff egg farm operators showed that farm expenses remained stable

during the period of decreased production resulting from defendant’s

contaminated feed). 

The jury here awarded Southern States lost profits of $770,229.30—an

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amount equal to its alleged lost revenues. Lisa Della Monica of Southern States

testified that Southern States’s expenses remained stable during the time period at

issue in this case. Melick argues (without pointing to any evidence in support)

that her testimony must be incorrect because there are a number of variable costs

associated with raising fish. Because the jury was entitled to credit Della

Monica’s testimony as true, and therefore was permitted to conclude that lost

revenues equaled lost profits, Bennett, 267 S.E.2d at 20, we affirm.

AFFIRMED.

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